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Posted to commits@cassandra.apache.org by sl...@apache.org on 2014/06/30 11:09:20 UTC
svn commit: r1606650 - /cassandra/site/publish/doc/cql3/CQL-2.0.html
Author: slebresne
Date: Mon Jun 30 09:09:19 2014
New Revision: 1606650
URL: http://svn.apache.org/r1606650
Log:
Update CQL doc
Modified:
cassandra/site/publish/doc/cql3/CQL-2.0.html
Modified: cassandra/site/publish/doc/cql3/CQL-2.0.html
URL: http://svn.apache.org/viewvc/cassandra/site/publish/doc/cql3/CQL-2.0.html?rev=1606650&r1=1606649&r2=1606650&view=diff
==============================================================================
--- cassandra/site/publish/doc/cql3/CQL-2.0.html (original)
+++ cassandra/site/publish/doc/cql3/CQL-2.0.html Mon Jun 30 09:09:19 2014
@@ -101,7 +101,7 @@ CREATE TABLE timeline (
INSERT INTO test(pk, t, v, s) VALUES (0, 0, 'val0', 'static0');
INSERT INTO test(pk, t, v, s) VALUES (0, 1, 'val1', 'static1');
SELECT * FROM test WHERE pk=0 AND t=0;
-</pre></pre><p>the last query will return <code>'static1'</code> as value for <code>s</code>, since <code>s</code> is static and thus the 2nd insertion modified this “shared” value. Note however that static columns are only static within a given partition, and if in the example above both rows where from different partitions (i.e. if they had different value for <code>pk</code>), then the 2nd insertion would not have modified the value of <code>s</code> for the first row.</p><p>A few restrictions applies to when static columns are allowed:</p><ul><li>tables with the <code>COMPACT STORAGE</code> option (see below) cannot have them</li><li>a table without clustering columns cannot have static columns (in a table without clustering columns, every partition has only one row, and so every column is inherently static).</li><li>only non <code>PRIMARY KEY</code> columns can be static</li></ul><h4 id="createTableOptions"><code><option></code></h4><p>The <code>CREATE TABLE</cod
e> statement supports a number of options that controls the configuration of a new table. These options can be specified after the <code>WITH</code> keyword.</p><p>The first of these option is <code>COMPACT STORAGE</code>. This option is mainly targeted towards backward compatibility for definitions created before CQL3 (see <a href="http://www.datastax.com/dev/blog/thrift-to-cql3">www.datastax.com/dev/blog/thrift-to-cql3</a> for more details). The option also provides a slightly more compact layout of data on disk but at the price of diminished flexibility and extensibility for the table. Most notably, <code>COMPACT STORAGE</code> tables cannot have collections nor static columns and a <code>COMPACT STORAGE</code> table with at least one clustering column supports exactly one (as in not 0 nor more than 1) column not part of the <code>PRIMARY KEY</code> definition (which imply in particular that you cannot add nor remove columns after creation). For those reasons, <code>COMPACT STO
RAGE</code> is not recommended outside of the backward compatibility reason evoked above.</p><p>Another option is <code>CLUSTERING ORDER</code>. It allows to define the ordering of rows on disk. It takes the list of the clustering column names with, for each of them, the on-disk order (Ascending or descending). Note that this option affects <a href="#selectOrderBy">what <code>ORDER BY</code> are allowed during <code>SELECT</code></a>.</p><p>Table creation supports the following other <code><property></code>:</p><table><tr><th>option </th><th>kind </th><th>default </th><th>description</th></tr><tr><td><code>comment</code> </td><td><em>simple</em> </td><td>none </td><td>A free-form, human-readable comment.</td></tr><tr><td><code>read_repair_chance</code> </td><td><em>simple</em> </td><td>0.1 </td><td>The probability with which to query extra nodes (e.g. more nodes than required by the consistency level) for the purpos
e of read repairs.</td></tr><tr><td><code>dclocal_read_repair_chance</code> </td><td><em>simple</em> </td><td>0 </td><td>The probability with which to query extra nodes (e.g. more nodes than required by the consistency level) belonging to the same data center than the read coordinator for the purpose of read repairs.</td></tr><tr><td><code>gc_grace_seconds</code> </td><td><em>simple</em> </td><td>864000 </td><td>Time to wait before garbage collecting tombstones (deletion markers).</td></tr><tr><td><code>bloom_filter_fp_chance</code> </td><td><em>simple</em> </td><td>0.00075 </td><td>The target probability of false positive of the sstable bloom filters. Said bloom filters will be sized to provide the provided probability (thus lowering this value impact the size of bloom filters in-memory and on-disk)</td></tr><tr><td><code>compaction</code> </td><td><em>map</em> </td><td><em>see below</em> </td><td>The compaction options to use, se
e below.</td></tr><tr><td><code>compression</code> </td><td><em>map</em> </td><td><em>see below</em> </td><td>Compression options, see below. </td></tr><tr><td><code>replicate_on_write</code> </td><td><em>simple</em> </td><td>true </td><td>Whether to replicate data on write. This can only be set to false for tables with counters values. Disabling this is dangerous and can result in random lose of counters, don’t disable unless you are sure to know what you are doing</td></tr><tr><td><code>caching</code> </td><td><em>simple</em> </td><td>keys_only </td><td>Whether to cache keys (“key cache”) and/or rows (“row cache”) for this table. Valid values are: <code>all</code>, <code>keys_only</code>, <code>rows_only</code> and <code>none</code>. </td></tr></table><h4 id="compactionOptions"><code>compaction</code> options</h4><p>The <code>compaction</code> property must at least define the <code>'class'</code>
sub-option, that defines the compaction strategy class to use. The default supported class are <code>'SizeTieredCompactionStrategy'</code> and <code>'LeveledCompactionStrategy'</code>. Custom strategy can be provided by specifying the full class name as a <a href="#constants">string constant</a>. The rest of the sub-options depends on the chosen class. The sub-options supported by the default classes are:</p><table><tr><th>option </th><th>supported compaction strategy </th><th>default </th><th>description </th></tr><tr><td><code>enabled</code> </td><td><em>all</em> </td><td>true </td><td>A boolean denoting whether compaction should be enabled or not.</td></tr><tr><td><code>tombstone_threshold</code> </td><td><em>all</em> </td><td>0.2 </td><td>A ratio such that if a sstable has more than this ratio of gcable tombstones over all contained columns, the sstable will be c
ompacted (with no other sstables) for the purpose of purging those tombstones. </td></tr><tr><td><code>tombstone_compaction_interval</code> </td><td><em>all</em> </td><td>1 day </td><td>The minimum time to wait after an sstable creation time before considering it for “tombstone compaction”, where “tombstone compaction” is the compaction triggered if the sstable has more gcable tombstones than <code>tombstone_threshold</code>. </td></tr><tr><td><code>min_sstable_size</code> </td><td>SizeTieredCompactionStrategy </td><td>50MB </td><td>The size tiered strategy groups SSTables to compact in buckets. A bucket groups SSTables that differs from less than 50% in size. However, for small sizes, this would result in a bucketing that is too fine grained. <code>min_sstable_size</code> defines a size threshold (in bytes) below which all SSTables belong to one unique bucket</td></tr><tr><td><code>min_threshold</code>
</td><td>SizeTieredCompactionStrategy </td><td>4 </td><td>Minimum number of SSTables needed to start a minor compaction.</td></tr><tr><td><code>max_threshold</code> </td><td>SizeTieredCompactionStrategy </td><td>32 </td><td>Maximum number of SSTables processed by one minor compaction.</td></tr><tr><td><code>bucket_low</code> </td><td>SizeTieredCompactionStrategy </td><td>0.5 </td><td>Size tiered consider sstables to be within the same bucket if their size is within [average_size * <code>bucket_low</code>, average_size * <code>bucket_high</code> ] (i.e the default groups sstable whose sizes diverges by at most 50%)</td></tr><tr><td><code>bucket_high</code> </td><td>SizeTieredCompactionStrategy </td><td>1.5 </td><td>Size tiered consider sstables to be within the same bucket if their size is within [average_size * <code>bucket_low</code>, average_size * <code>bucket_high</code> ] (i.
e the default groups sstable whose sizes diverges by at most 50%).</td></tr><tr><td><code>sstable_size_in_mb</code> </td><td>LeveledCompactionStrategy </td><td>5MB </td><td>The target size (in MB) for sstables in the leveled strategy. Note that while sstable sizes should stay less or equal to <code>sstable_size_in_mb</code>, it is possible to exceptionally have a larger sstable as during compaction, data for a given partition key are never split into 2 sstables</td></tr></table><p>For the <code>compression</code> property, the following default sub-options are available:</p><table><tr><th>option </th><th>default </th><th>description </th></tr><tr><td><code>sstable_compression</code> </td><td>LZ4Compressor </td><td>The compression algorithm to use. Default compressor are: LZ4Compressor, SnappyCompressor and DeflateCompressor. Use an empty string (<code>''</code>) to disable compression. Custom compressor can be provided by specifying the
full class name as a <a href="#constants">string constant</a>.</td></tr><tr><td><code>chunk_length_kb</code> </td><td>64KB </td><td>On disk SSTables are compressed by block (to allow random reads). This defines the size (in KB) of said block. Bigger values may improve the compression rate, but increases the minimum size of data to be read from disk for a read </td></tr><tr><td><code>crc_check_chance</code> </td><td>1.0 </td><td>When compression is enabled, each compressed block includes a checksum of that block for the purpose of detecting disk bitrot and avoiding the propagation of corruption to other replica. This option defines the probability with which those checksums are checked during read. By default they are always checked. Set to 0 to disable checksum checking and to 0.5 for instance to check them every other read</td></tr></table><h4 id="Otherconsiderations">Other considerations:</h4><ul><li>When <a href="#insertStmt/"updating":#u
pdateStmt">inserting</a> a given row, not all columns needs to be defined (except for those part of the key), and missing columns occupy no space on disk. Furthermore, adding new columns (see <a href=#alterStmt><tt>ALTER TABLE</tt></a>) is a constant time operation. There is thus no need to try to anticipate future usage (or to cry when you haven’t) when creating a table.</li></ul><h3 id="alterTableStmt">ALTER TABLE</h3><p><i>Syntax:</i></p><pre class="syntax"><pre><alter-table-stmt> ::= ALTER (TABLE | COLUMNFAMILY) <tablename> <instruction>
+</pre></pre><p>the last query will return <code>'static1'</code> as value for <code>s</code>, since <code>s</code> is static and thus the 2nd insertion modified this “shared” value. Note however that static columns are only static within a given partition, and if in the example above both rows where from different partitions (i.e. if they had different value for <code>pk</code>), then the 2nd insertion would not have modified the value of <code>s</code> for the first row.</p><p>A few restrictions applies to when static columns are allowed:</p><ul><li>tables with the <code>COMPACT STORAGE</code> option (see below) cannot have them</li><li>a table without clustering columns cannot have static columns (in a table without clustering columns, every partition has only one row, and so every column is inherently static).</li><li>only non <code>PRIMARY KEY</code> columns can be static</li></ul><h4 id="createTableOptions"><code><option></code></h4><p>The <code>CREATE TABLE</cod
e> statement supports a number of options that controls the configuration of a new table. These options can be specified after the <code>WITH</code> keyword.</p><p>The first of these option is <code>COMPACT STORAGE</code>. This option is mainly targeted towards backward compatibility for definitions created before CQL3 (see <a href="http://www.datastax.com/dev/blog/thrift-to-cql3">www.datastax.com/dev/blog/thrift-to-cql3</a> for more details). The option also provides a slightly more compact layout of data on disk but at the price of diminished flexibility and extensibility for the table. Most notably, <code>COMPACT STORAGE</code> tables cannot have collections nor static columns and a <code>COMPACT STORAGE</code> table with at least one clustering column supports exactly one (as in not 0 nor more than 1) column not part of the <code>PRIMARY KEY</code> definition (which imply in particular that you cannot add nor remove columns after creation). For those reasons, <code>COMPACT STO
RAGE</code> is not recommended outside of the backward compatibility reason evoked above.</p><p>Another option is <code>CLUSTERING ORDER</code>. It allows to define the ordering of rows on disk. It takes the list of the clustering column names with, for each of them, the on-disk order (Ascending or descending). Note that this option affects <a href="#selectOrderBy">what <code>ORDER BY</code> are allowed during <code>SELECT</code></a>.</p><p>Table creation supports the following other <code><property></code>:</p><table><tr><th>option </th><th>kind </th><th>default </th><th>description</th></tr><tr><td><code>comment</code> </td><td><em>simple</em> </td><td>none </td><td>A free-form, human-readable comment.</td></tr><tr><td><code>read_repair_chance</code> </td><td><em>simple</em> </td><td>0.1 </td><td>The probability with which to query extra nodes (e.g. more nodes than required by the consistency level) for the purpos
e of read repairs.</td></tr><tr><td><code>dclocal_read_repair_chance</code> </td><td><em>simple</em> </td><td>0 </td><td>The probability with which to query extra nodes (e.g. more nodes than required by the consistency level) belonging to the same data center than the read coordinator for the purpose of read repairs.</td></tr><tr><td><code>gc_grace_seconds</code> </td><td><em>simple</em> </td><td>864000 </td><td>Time to wait before garbage collecting tombstones (deletion markers).</td></tr><tr><td><code>bloom_filter_fp_chance</code> </td><td><em>simple</em> </td><td>0.00075 </td><td>The target probability of false positive of the sstable bloom filters. Said bloom filters will be sized to provide the provided probability (thus lowering this value impact the size of bloom filters in-memory and on-disk)</td></tr><tr><td><code>compaction</code> </td><td><em>map</em> </td><td><em>see below</em> </td><td>The compaction options to use, se
e below.</td></tr><tr><td><code>compression</code> </td><td><em>map</em> </td><td><em>see below</em> </td><td>Compression options, see below. </td></tr><tr><td><code>replicate_on_write</code> </td><td><em>simple</em> </td><td>true </td><td>Whether to replicate data on write. This can only be set to false for tables with counters values. Disabling this is dangerous and can result in random lose of counters, don’t disable unless you are sure to know what you are doing</td></tr><tr><td><code>caching</code> </td><td><em>simple</em> </td><td>keys_only </td><td>Whether to cache keys (“key cache”) and/or rows (“row cache”) for this table. Valid values are: <code>all</code>, <code>keys_only</code>, <code>rows_only</code> and <code>none</code>. </td></tr></table><h4 id="compactionOptions"><code>compaction</code> options</h4><p>The <code>compaction</code> property must at least define the <code>'class'</code>
sub-option, that defines the compaction strategy class to use. The default supported class are <code>'SizeTieredCompactionStrategy'</code> and <code>'LeveledCompactionStrategy'</code>. Custom strategy can be provided by specifying the full class name as a <a href="#constants">string constant</a>. The rest of the sub-options depends on the chosen class. The sub-options supported by the default classes are:</p><table><tr><th>option </th><th>supported compaction strategy </th><th>default </th><th>description </th></tr><tr><td><code>enabled</code> </td><td><em>all</em> </td><td>true </td><td>A boolean denoting whether compaction should be enabled or not.</td></tr><tr><td><code>tombstone_threshold</code> </td><td><em>all</em> </td><td>0.2 </td><td>A ratio such that if a sstable has more than this ratio of gcable tombstones over all contained columns, the sstable will b
e compacted (with no other sstables) for the purpose of purging those tombstones. </td></tr><tr><td><code>tombstone_compaction_interval</code> </td><td><em>all</em> </td><td>1 day </td><td>The minimum time to wait after an sstable creation time before considering it for “tombstone compaction”, where “tombstone compaction” is the compaction triggered if the sstable has more gcable tombstones than <code>tombstone_threshold</code>. </td></tr><tr><td><code>unchecked_tombstone_compaction</code> </td><td><em>all</em> </td><td>false </td><td>Setting this to true enables more aggressive tombstone compactions – single sstable tombstone compactions will run without checking how likely it is that they will be successful. </td></tr><tr><td><code>min_sstable_size</code> </td><td>SizeTieredCompactionStrategy </td><td>50MB </td><td>The size tiered strategy groups SSTables to compact in b
uckets. A bucket groups SSTables that differs from less than 50% in size. However, for small sizes, this would result in a bucketing that is too fine grained. <code>min_sstable_size</code> defines a size threshold (in bytes) below which all SSTables belong to one unique bucket</td></tr><tr><td><code>min_threshold</code> </td><td>SizeTieredCompactionStrategy </td><td>4 </td><td>Minimum number of SSTables needed to start a minor compaction.</td></tr><tr><td><code>max_threshold</code> </td><td>SizeTieredCompactionStrategy </td><td>32 </td><td>Maximum number of SSTables processed by one minor compaction.</td></tr><tr><td><code>bucket_low</code> </td><td>SizeTieredCompactionStrategy </td><td>0.5 </td><td>Size tiered consider sstables to be within the same bucket if their size is within [average_size * <code>bucket_low</code>, average_size * <code>bucket_high</code> ] (i.e the default groups sstable whose
sizes diverges by at most 50%)</td></tr><tr><td><code>bucket_high</code> </td><td>SizeTieredCompactionStrategy </td><td>1.5 </td><td>Size tiered consider sstables to be within the same bucket if their size is within [average_size * <code>bucket_low</code>, average_size * <code>bucket_high</code> ] (i.e the default groups sstable whose sizes diverges by at most 50%).</td></tr><tr><td><code>sstable_size_in_mb</code> </td><td>LeveledCompactionStrategy </td><td>5MB </td><td>The target size (in MB) for sstables in the leveled strategy. Note that while sstable sizes should stay less or equal to <code>sstable_size_in_mb</code>, it is possible to exceptionally have a larger sstable as during compaction, data for a given partition key are never split into 2 sstables</td></tr></table><p>For the <code>compression</code> property, the following default sub-options are available:</p><table><tr><th>option </th><th>default </
th><th>description </th></tr><tr><td><code>sstable_compression</code> </td><td>LZ4Compressor </td><td>The compression algorithm to use. Default compressor are: LZ4Compressor, SnappyCompressor and DeflateCompressor. Use an empty string (<code>''</code>) to disable compression. Custom compressor can be provided by specifying the full class name as a <a href="#constants">string constant</a>.</td></tr><tr><td><code>chunk_length_kb</code> </td><td>64KB </td><td>On disk SSTables are compressed by block (to allow random reads). This defines the size (in KB) of said block. Bigger values may improve the compression rate, but increases the minimum size of data to be read from disk for a read </td></tr><tr><td><code>crc_check_chance</code> </td><td>1.0 </td><td>When compression is enabled, each compressed block includes a checksum of that block for the purpose of detecting disk bitrot and avoiding the propagation of corruption to other replica. This option de
fines the probability with which those checksums are checked during read. By default they are always checked. Set to 0 to disable checksum checking and to 0.5 for instance to check them every other read</td></tr></table><h4 id="Otherconsiderations">Other considerations:</h4><ul><li>When <a href="#insertStmt/"updating":#updateStmt">inserting</a> a given row, not all columns needs to be defined (except for those part of the key), and missing columns occupy no space on disk. Furthermore, adding new columns (see <a href=#alterStmt><tt>ALTER TABLE</tt></a>) is a constant time operation. There is thus no need to try to anticipate future usage (or to cry when you haven’t) when creating a table.</li></ul><h3 id="alterTableStmt">ALTER TABLE</h3><p><i>Syntax:</i></p><pre class="syntax"><pre><alter-table-stmt> ::= ALTER (TABLE | COLUMNFAMILY) <tablename> <instruction>
<instruction> ::= ALTER <identifier> TYPE <type>
| ADD <identifier> <type>
@@ -348,4 +348,4 @@ UPDATE plays SET scores = scores - [ 12,
)
</pre></pre><p>then the <code>token</code> function will take a single argument of type <code>text</code> (in that case, the partition key is <code>userid</code> (there is no clustering columns so the partition key is the same than the primary key)), and the return type will be <code>bigint</code>.</p><h3 id="uuidFun">Uuid</h3><p>The <code>uuid</code> function takes no parameters and generates a random type 4 uuid suitable for use in INSERT or SET statements.</p><h3 id="timeuuidFun">Timeuuid functions</h3><h4 id="now"><code>now</code></h4><p>The <code>now</code> function takes no arguments and generates a new unique timeuuid (at the time where the statement using it is executed). Note that this method is useful for insertion but is largely non-sensical in <code>WHERE</code> clauses. For instance, a query of the form</p><pre class="sample"><pre>SELECT * FROM myTable WHERE t = now()
</pre></pre><p>will never return any result by design, since the value returned by <code>now()</code> is guaranteed to be unique.</p><h4 id="minTimeuuidandmaxTimeuuid"><code>minTimeuuid</code> and <code>maxTimeuuid</code></h4><p>The <code>minTimeuuid</code> (resp. <code>maxTimeuuid</code>) function takes a <code>timestamp</code> value <code>t</code> (which can be <a href="#usingdates">either a timestamp or a date string</a>) and return a <em>fake</em> <code>timeuuid</code> corresponding to the <em>smallest</em> (resp. <em>biggest</em>) possible <code>timeuuid</code> having for timestamp <code>t</code>. So for instance:</p> <pre class="sample"><pre>SELECT * FROM myTable WHERE t > maxTimeuuid('2013-01-01 00:05+0000') AND t < minTimeuuid('2013-02-02 10:00+0000')
-</pre></pre> <p>will select all rows where the <code>timeuuid</code> column <code>t</code> is strictly older than ‘2013-01-01 00:05+0000’ but strictly younger than ‘2013-02-02 10:00+0000’. Please note that <code>t >= maxTimeuuid('2013-01-01 00:05+0000')</code> would still <em>not</em> select a <code>timeuuid</code> generated exactly at ‘2013-01-01 00:05+0000’ and is essentially equivalent to <code>t > maxTimeuuid('2013-01-01 00:05+0000')</code>.</p><p><em>Warning</em>: We called the values generated by <code>minTimeuuid</code> and <code>maxTimeuuid</code> <em>fake</em> UUID because they do no respect the Time-Based UUID generation process specified by the <a href="http://www.ietf.org/rfc/rfc4122.txt">RFC 4122</a>. In particular, the value returned by these 2 methods will not be unique. This means you should only use those methods for querying (as in the example above). Inserting the result of those methods is almost certainly <em>a bad idea</em>.
</p><h4 id="dateOfandunixTimestampOf"><code>dateOf</code> and <code>unixTimestampOf</code></h4><p>The <code>dateOf</code> and <code>unixTimestampOf</code> functions take a <code>timeuuid</code> argument and extract the embedded timestamp. However, while the <code>dateof</code> function return it with the <code>timestamp</code> type (that most client, including cqlsh, interpret as a date), the <code>unixTimestampOf</code> function returns it as a <code>bigint</code> raw value.</p><h3 id="blobFun">Blob conversion functions</h3><p>A number of functions are provided to “convert” the native types into binary data (<code>blob</code>). For every <code><native-type></code> <code>type</code> supported by CQL3 (a notable exceptions is <code>blob</code>, for obvious reasons), the function <code>typeAsBlob</code> takes a argument of type <code>type</code> and return it as a <code>blob</code>. Conversely, the function <code>blobAsType</code> takes a 64-bit <code>blob</code> argum
ent and convert it to a <code>bigint</code> value. And so for instance, <code>bigintAsBlob(3)</code> is <code>0x0000000000000003</code> and <code>blobAsBigint(0x0000000000000003)</code> is <code>3</code>.</p><h2 id="appendixA">Appendix A: CQL Keywords</h2><p>CQL distinguishes between <em>reserved</em> and <em>non-reserved</em> keywords. Reserved keywords cannot be used as identifier, they are truly reserved for the language (but one can enclose a reserved keyword by double-quotes to use it as an identifier). Non-reserved keywords however only have a specific meaning in certain context but can used as identifer otherwise. The only <em>raison d'être</em> of these non-reserved keywords is convenience: some keyword are non-reserved when it was always easy for the parser to decide whether they were used as keywords or not.</p><table><tr><th>Keyword </th><th>Reserved? </th></tr><tr><td><code>ADD</code> </td><td>yes </td></tr><tr><td><code>ALL</code> </td><td>no
</td></tr><tr><td><code>ALTER</code> </td><td>yes </td></tr><tr><td><code>AND</code> </td><td>yes </td></tr><tr><td><code>ANY</code> </td><td>yes </td></tr><tr><td><code>APPLY</code> </td><td>yes </td></tr><tr><td><code>AS</code> </td><td>no </td></tr><tr><td><code>ASC</code> </td><td>yes </td></tr><tr><td><code>ASCII</code> </td><td>no </td></tr><tr><td><code>AUTHORIZE</code> </td><td>yes </td></tr><tr><td><code>BATCH</code> </td><td>yes </td></tr><tr><td><code>BEGIN</code> </td><td>yes </td></tr><tr><td><code>BIGINT</code> </td><td>no </td></tr><tr><td><code>BLOB</code> </td><td>no </td></tr><tr><td><code>BOOLEAN</code> </td><td>no </td></tr><tr><td><code>BY</code> </td><td>yes </td></tr><tr><td><code>CLUSTERING</code> </td><td>no </td></tr><tr><td><code>COLUMNFAMILY</code> </td><td>yes </td></tr><tr><td><code>COMPACT</code> </td><td>no </td></tr><tr><td><code>CON
SISTENCY</code> </td><td>no </td></tr><tr><td><code>COUNT</code> </td><td>no </td></tr><tr><td><code>COUNTER</code> </td><td>no </td></tr><tr><td><code>CREATE</code> </td><td>yes </td></tr><tr><td><code>DECIMAL</code> </td><td>no </td></tr><tr><td><code>DELETE</code> </td><td>yes </td></tr><tr><td><code>DESC</code> </td><td>yes </td></tr><tr><td><code>DOUBLE</code> </td><td>no </td></tr><tr><td><code>DROP</code> </td><td>yes </td></tr><tr><td><code>EACH_QUORUM</code> </td><td>yes </td></tr><tr><td><code>FLOAT</code> </td><td>no </td></tr><tr><td><code>FROM</code> </td><td>yes </td></tr><tr><td><code>GRANT</code> </td><td>yes </td></tr><tr><td><code>IN</code> </td><td>yes </td></tr><tr><td><code>INDEX</code> </td><td>yes </td></tr><tr><td><code>CUSTOM</code> </td><td>no </td></tr><tr><td><code>INSERT</code> </td><td>yes </td></tr><tr><td><code>INT</code> </td><td>no
</td></tr><tr><td><code>INTO</code> </td><td>yes </td></tr><tr><td><code>KEY</code> </td><td>no </td></tr><tr><td><code>KEYSPACE</code> </td><td>yes </td></tr><tr><td><code>LEVEL</code> </td><td>no </td></tr><tr><td><code>LIMIT</code> </td><td>yes </td></tr><tr><td><code>LOCAL_ONE</code> </td><td>yes </td></tr><tr><td><code>LOCAL_QUORUM</code> </td><td>yes </td></tr><tr><td><code>MODIFY</code> </td><td>yes </td></tr><tr><td><code>NORECURSIVE</code> </td><td>yes </td></tr><tr><td><code>NOSUPERUSER</code> </td><td>no </td></tr><tr><td><code>OF</code> </td><td>yes </td></tr><tr><td><code>ON</code> </td><td>yes </td></tr><tr><td><code>ONE</code> </td><td>yes </td></tr><tr><td><code>ORDER</code> </td><td>yes </td></tr><tr><td><code>PASSWORD</code> </td><td>no </td></tr><tr><td><code>PERMISSION</code> </td><td>no </td></tr><tr><td><code>PERMISSIONS</code> </td><td>no </td></tr><tr><td><code>PR
IMARY</code> </td><td>yes </td></tr><tr><td><code>QUORUM</code> </td><td>yes </td></tr><tr><td><code>REVOKE</code> </td><td>yes </td></tr><tr><td><code>SCHEMA</code> </td><td>yes </td></tr><tr><td><code>SELECT</code> </td><td>yes </td></tr><tr><td><code>SET</code> </td><td>yes </td></tr><tr><td><code>STORAGE</code> </td><td>no </td></tr><tr><td><code>SUPERUSER</code> </td><td>no </td></tr><tr><td><code>TABLE</code> </td><td>yes </td></tr><tr><td><code>TEXT</code> </td><td>no </td></tr><tr><td><code>TIMESTAMP</code> </td><td>no </td></tr><tr><td><code>TIMEUUID</code> </td><td>no </td></tr><tr><td><code>THREE</code> </td><td>yes </td></tr><tr><td><code>TOKEN</code> </td><td>yes </td></tr><tr><td><code>TRUNCATE</code> </td><td>yes </td></tr><tr><td><code>TTL</code> </td><td>no </td></tr><tr><td><code>TWO</code> </td><td>yes </td></tr><tr><td><code>TYPE</code> </td><td>n
o </td></tr><tr><td><code>UPDATE</code> </td><td>yes </td></tr><tr><td><code>USE</code> </td><td>yes </td></tr><tr><td><code>USER</code> </td><td>no </td></tr><tr><td><code>USERS</code> </td><td>no </td></tr><tr><td><code>USING</code> </td><td>yes </td></tr><tr><td><code>UUID</code> </td><td>no </td></tr><tr><td><code>VALUES</code> </td><td>no </td></tr><tr><td><code>VARCHAR</code> </td><td>no </td></tr><tr><td><code>VARINT</code> </td><td>no </td></tr><tr><td><code>WHERE</code> </td><td>yes </td></tr><tr><td><code>WITH</code> </td><td>yes </td></tr><tr><td><code>WRITETIME</code> </td><td>no </td></tr><tr><td><code>DISTINCT</code> </td><td>no </td></tr></table><h2 id="changes">Changes</h2><p>The following describes the addition/changes brought for each version of CQL.</p><h3 id="a3.1.7">3.1.7</h3><ul><li><code>SELECT</code> statements now support selecting multiple rows in a single partition
using an <code>IN</code> clause on combinations of clustering columns. See <a href="#selectWhere">SELECT WHERE</a> clauses.</li></ul><h3 id="a3.1.6">3.1.6</h3><ul><li>A new <a href="#uuidFun"><code>uuid</code> method</a> has been added.</li><li>Support for <code>DELETE ... IF EXISTS</code> syntax.</li></ul><h3 id="a3.1.5">3.1.5</h3><ul><li>It is now possible to group clustering columns in a relatiion, see <a href="#selectWhere">SELECT WHERE</a> clauses.</li><li>Added support for <code>STATIC</code> columns, see <a href="#createTableStatic">static in CREATE TABLE</a>.</li></ul><h3 id="a3.1.4">3.1.4</h3><ul><li><code>CREATE INDEX</code> now allows specifying options when creating CUSTOM indexes (see <a href="#createIndexStmt">CREATE INDEX reference</a>).</li></ul><h3 id="a3.1.3">3.1.3</h3><ul><li>Millisecond precision formats have been added to the timestamp parser (see <a href="#usingdates">working with dates</a>).</li></ul><h3 id="a3.1.2">3.1.2</h3><ul><li><code>NaN</code> and <co
de>Infinity</code> has been added as valid float contants. They are now reserved keywords. In the unlikely case you we using them as a column identifier (or keyspace/table one), you will noew need to double quote them (see <a href="#identifiers">quote identifiers</a>).</li></ul><h3 id="a3.1.1">3.1.1</h3><ul><li><code>SELECT</code> statement now allows listing the partition keys (using the <code>DISTINCT</code> modifier). See <a href="https://issues.apache.org/jira/browse/CASSANDRA-4536">CASSANDRA-4536</a>.</li><li>The syntax <code>c IN ?</code> is now supported in <code>WHERE</code> clauses. In that case, the value expected for the bind variable will be a list of whatever type <code>c</code> is.</li><li>It is now possible to use named bind variables (using <code>:name</code> instead of <code>?</code>).</li></ul><h3 id="a3.1.0">3.1.0</h3><ul><li><a href="#alterTableStmt">ALTER TABLE</a> <code>DROP</code> option has been reenabled for CQL3 tables and has new semantics now: the space f
ormerly used by dropped columns will now be eventually reclaimed (post-compaction). You should not readd previously dropped columns unless you use timestamps with microsecond precision (see <a href="https://issues.apache.org/jira/browse/CASSANDRA-3919">CASSANDRA-3919</a> for more details).</li><li><code>SELECT</code> statement now supports aliases in select clause. Aliases in WHERE and ORDER BY clauses are not supported. See the “section on select”#selectStmt for details.</li><li><code>CREATE</code> statements for <code>KEYSPACE</code>, <code>TABLE</code> and <code>INDEX</code> now supports an <code>IF NOT EXISTS</code> condition. Similarly, <code>DROP</code> statements support a <code>IF EXISTS</code> condition.</li><li><code>INSERT</code> statements optionally supports a <code>IF NOT EXISTS</code> condition and <code>UPDATE</code> supports <code>IF</code> conditions.</li></ul><h3 id="a3.0.5">3.0.5</h3><ul><li><code>SELECT</code>, <code>UPDATE</code>, and <code>DELETE</
code> statements now allow empty <code>IN</code> relations (see <a href="https://issues.apache.org/jira/browse/CASSANDRA-5626">CASSANDRA-5626</a>).</li></ul><h3 id="a3.0.4">3.0.4</h3><ul><li>Updated the syntax for custom <a href="#createIndexStmt">secondary indexes</a>.</li><li>Non-equal condition on the partition key are now never supported, even for ordering partitioner as this was not correct (the order was <strong>not</strong> the one of the type of the partition key). Instead, the <code>token</code> method should always be used for range queries on the partition key (see <a href="#selectWhere">WHERE clauses</a>).</li></ul><h3 id="a3.0.3">3.0.3</h3><ul><li>Support for custom <a href="#createIndexStmt">secondary indexes</a> has been added.</li></ul><h3 id="a3.0.2">3.0.2</h3><ul><li>Type validation for the <a href="#constants">constants</a> has been fixed. For instance, the implementation used to allow <code>'2'</code> as a valid value for an <code>int</code> column (interpreting
it has the equivalent of <code>2</code>), or <code>42</code> as a valid <code>blob</code> value (in which case <code>42</code> was interpreted as an hexadecimal representation of the blob). This is no longer the case, type validation of constants is now more strict. See the <a href="#types">data types</a> section for details on which constant is allowed for which type.</li><li>The type validation fixed of the previous point has lead to the introduction of <a href="#constants">blobs constants</a> to allow inputing blobs. Do note that while inputing blobs as strings constant is still supported by this version (to allow smoother transition to blob constant), it is now deprecated (in particular the <a href="#types">data types</a> section does not list strings constants as valid blobs) and will be removed by a future version. If you were using strings as blobs, you should thus update your client code ASAP to switch blob constants.</li><li>A number of functions to convert native types to
blobs have also been introduced. Furthermore the token function is now also allowed in select clauses. See the <a href="#functions">section on functions</a> for details.</li></ul><h3 id="a3.0.1">3.0.1</h3><ul><li><a href="#usingdates">Date strings</a> (and timestamps) are no longer accepted as valid <code>timeuuid</code> values. Doing so was a bug in the sense that date string are not valid <code>timeuuid</code>, and it was thus resulting in <a href="https://issues.apache.org/jira/browse/CASSANDRA-4936">confusing behaviors</a>. However, the following new methods have been added to help working with <code>timeuuid</code>: <code>now</code>, <code>minTimeuuid</code>, <code>maxTimeuuid</code> , <code>dateOf</code> and <code>unixTimestampOf</code>. See the <a href="#usingtimeuuid">section dedicated to these methods</a> for more detail.</li><li>“Float constants”#constants now support the exponent notation. In other words, <code>4.2E10</code> is now a valid floating point valu
e.</li></ul><h2 id="Versioning">Versioning</h2><p>Versioning of the CQL language adheres to the <a href="http://semver.org">Semantic Versioning</a> guidelines. Versions take the form X.Y.Z where X, Y, and Z are integer values representing major, minor, and patch level respectively. There is no correlation between Cassandra release versions and the CQL language version.</p><table><tr><th>version</th><th>description</th></tr><tr><td>Major </td><td>The major version <em>must</em> be bumped when backward incompatible changes are introduced. This should rarely occur.</td></tr><tr><td>Minor </td><td>Minor version increments occur when new, but backward compatible, functionality is introduced.</td></tr><tr><td>Patch </td><td>The patch version is incremented when bugs are fixed.</td></tr></table></body></html>
\ No newline at end of file
+</pre></pre> <p>will select all rows where the <code>timeuuid</code> column <code>t</code> is strictly older than ‘2013-01-01 00:05+0000’ but strictly younger than ‘2013-02-02 10:00+0000’. Please note that <code>t >= maxTimeuuid('2013-01-01 00:05+0000')</code> would still <em>not</em> select a <code>timeuuid</code> generated exactly at ‘2013-01-01 00:05+0000’ and is essentially equivalent to <code>t > maxTimeuuid('2013-01-01 00:05+0000')</code>.</p><p><em>Warning</em>: We called the values generated by <code>minTimeuuid</code> and <code>maxTimeuuid</code> <em>fake</em> UUID because they do no respect the Time-Based UUID generation process specified by the <a href="http://www.ietf.org/rfc/rfc4122.txt">RFC 4122</a>. In particular, the value returned by these 2 methods will not be unique. This means you should only use those methods for querying (as in the example above). Inserting the result of those methods is almost certainly <em>a bad idea</em>.
</p><h4 id="dateOfandunixTimestampOf"><code>dateOf</code> and <code>unixTimestampOf</code></h4><p>The <code>dateOf</code> and <code>unixTimestampOf</code> functions take a <code>timeuuid</code> argument and extract the embedded timestamp. However, while the <code>dateof</code> function return it with the <code>timestamp</code> type (that most client, including cqlsh, interpret as a date), the <code>unixTimestampOf</code> function returns it as a <code>bigint</code> raw value.</p><h3 id="blobFun">Blob conversion functions</h3><p>A number of functions are provided to “convert” the native types into binary data (<code>blob</code>). For every <code><native-type></code> <code>type</code> supported by CQL3 (a notable exceptions is <code>blob</code>, for obvious reasons), the function <code>typeAsBlob</code> takes a argument of type <code>type</code> and return it as a <code>blob</code>. Conversely, the function <code>blobAsType</code> takes a 64-bit <code>blob</code> argum
ent and convert it to a <code>bigint</code> value. And so for instance, <code>bigintAsBlob(3)</code> is <code>0x0000000000000003</code> and <code>blobAsBigint(0x0000000000000003)</code> is <code>3</code>.</p><h2 id="appendixA">Appendix A: CQL Keywords</h2><p>CQL distinguishes between <em>reserved</em> and <em>non-reserved</em> keywords. Reserved keywords cannot be used as identifier, they are truly reserved for the language (but one can enclose a reserved keyword by double-quotes to use it as an identifier). Non-reserved keywords however only have a specific meaning in certain context but can used as identifer otherwise. The only <em>raison d'être</em> of these non-reserved keywords is convenience: some keyword are non-reserved when it was always easy for the parser to decide whether they were used as keywords or not.</p><table><tr><th>Keyword </th><th>Reserved? </th></tr><tr><td><code>ADD</code> </td><td>yes </td></tr><tr><td><code>ALL</code> </td><td>no
</td></tr><tr><td><code>ALTER</code> </td><td>yes </td></tr><tr><td><code>AND</code> </td><td>yes </td></tr><tr><td><code>ANY</code> </td><td>yes </td></tr><tr><td><code>APPLY</code> </td><td>yes </td></tr><tr><td><code>AS</code> </td><td>no </td></tr><tr><td><code>ASC</code> </td><td>yes </td></tr><tr><td><code>ASCII</code> </td><td>no </td></tr><tr><td><code>AUTHORIZE</code> </td><td>yes </td></tr><tr><td><code>BATCH</code> </td><td>yes </td></tr><tr><td><code>BEGIN</code> </td><td>yes </td></tr><tr><td><code>BIGINT</code> </td><td>no </td></tr><tr><td><code>BLOB</code> </td><td>no </td></tr><tr><td><code>BOOLEAN</code> </td><td>no </td></tr><tr><td><code>BY</code> </td><td>yes </td></tr><tr><td><code>CLUSTERING</code> </td><td>no </td></tr><tr><td><code>COLUMNFAMILY</code> </td><td>yes </td></tr><tr><td><code>COMPACT</code> </td><td>no </td></tr><tr><td><code>CON
SISTENCY</code> </td><td>no </td></tr><tr><td><code>COUNT</code> </td><td>no </td></tr><tr><td><code>COUNTER</code> </td><td>no </td></tr><tr><td><code>CREATE</code> </td><td>yes </td></tr><tr><td><code>DECIMAL</code> </td><td>no </td></tr><tr><td><code>DELETE</code> </td><td>yes </td></tr><tr><td><code>DESC</code> </td><td>yes </td></tr><tr><td><code>DOUBLE</code> </td><td>no </td></tr><tr><td><code>DROP</code> </td><td>yes </td></tr><tr><td><code>EACH_QUORUM</code> </td><td>yes </td></tr><tr><td><code>FLOAT</code> </td><td>no </td></tr><tr><td><code>FROM</code> </td><td>yes </td></tr><tr><td><code>GRANT</code> </td><td>yes </td></tr><tr><td><code>IN</code> </td><td>yes </td></tr><tr><td><code>INDEX</code> </td><td>yes </td></tr><tr><td><code>CUSTOM</code> </td><td>no </td></tr><tr><td><code>INSERT</code> </td><td>yes </td></tr><tr><td><code>INT</code> </td><td>no
</td></tr><tr><td><code>INTO</code> </td><td>yes </td></tr><tr><td><code>KEY</code> </td><td>no </td></tr><tr><td><code>KEYSPACE</code> </td><td>yes </td></tr><tr><td><code>LEVEL</code> </td><td>no </td></tr><tr><td><code>LIMIT</code> </td><td>yes </td></tr><tr><td><code>LOCAL_ONE</code> </td><td>yes </td></tr><tr><td><code>LOCAL_QUORUM</code> </td><td>yes </td></tr><tr><td><code>MODIFY</code> </td><td>yes </td></tr><tr><td><code>NORECURSIVE</code> </td><td>yes </td></tr><tr><td><code>NOSUPERUSER</code> </td><td>no </td></tr><tr><td><code>OF</code> </td><td>yes </td></tr><tr><td><code>ON</code> </td><td>yes </td></tr><tr><td><code>ONE</code> </td><td>yes </td></tr><tr><td><code>ORDER</code> </td><td>yes </td></tr><tr><td><code>PASSWORD</code> </td><td>no </td></tr><tr><td><code>PERMISSION</code> </td><td>no </td></tr><tr><td><code>PERMISSIONS</code> </td><td>no </td></tr><tr><td><code>PR
IMARY</code> </td><td>yes </td></tr><tr><td><code>QUORUM</code> </td><td>yes </td></tr><tr><td><code>REVOKE</code> </td><td>yes </td></tr><tr><td><code>SCHEMA</code> </td><td>yes </td></tr><tr><td><code>SELECT</code> </td><td>yes </td></tr><tr><td><code>SET</code> </td><td>yes </td></tr><tr><td><code>STORAGE</code> </td><td>no </td></tr><tr><td><code>SUPERUSER</code> </td><td>no </td></tr><tr><td><code>TABLE</code> </td><td>yes </td></tr><tr><td><code>TEXT</code> </td><td>no </td></tr><tr><td><code>TIMESTAMP</code> </td><td>no </td></tr><tr><td><code>TIMEUUID</code> </td><td>no </td></tr><tr><td><code>THREE</code> </td><td>yes </td></tr><tr><td><code>TOKEN</code> </td><td>yes </td></tr><tr><td><code>TRUNCATE</code> </td><td>yes </td></tr><tr><td><code>TTL</code> </td><td>no </td></tr><tr><td><code>TWO</code> </td><td>yes </td></tr><tr><td><code>TYPE</code> </td><td>n
o </td></tr><tr><td><code>UPDATE</code> </td><td>yes </td></tr><tr><td><code>USE</code> </td><td>yes </td></tr><tr><td><code>USER</code> </td><td>no </td></tr><tr><td><code>USERS</code> </td><td>no </td></tr><tr><td><code>USING</code> </td><td>yes </td></tr><tr><td><code>UUID</code> </td><td>no </td></tr><tr><td><code>VALUES</code> </td><td>no </td></tr><tr><td><code>VARCHAR</code> </td><td>no </td></tr><tr><td><code>VARINT</code> </td><td>no </td></tr><tr><td><code>WHERE</code> </td><td>yes </td></tr><tr><td><code>WITH</code> </td><td>yes </td></tr><tr><td><code>WRITETIME</code> </td><td>no </td></tr><tr><td><code>DISTINCT</code> </td><td>no </td></tr></table><h2 id="changes">Changes</h2><p>The following describes the addition/changes brought for each version of CQL.</p><h3 id="a3.1.7">3.1.7</h3><ul><li><code>SELECT</code> statements now support selecting multiple rows in a single partition
using an <code>IN</code> clause on combinations of clustering columns. See <a href="#selectWhere">SELECT WHERE</a> clauses.</li><li><code>IF NOT EXISTS</code> and <code>IF EXISTS</code> syntax is now supported by <code>CREATE USER</code> and <code>DROP USER</code> statmenets, respectively.</li></ul><h3 id="a3.1.6">3.1.6</h3><ul><li>A new <a href="#uuidFun"><code>uuid</code> method</a> has been added.</li><li>Support for <code>DELETE ... IF EXISTS</code> syntax.</li></ul><h3 id="a3.1.5">3.1.5</h3><ul><li>It is now possible to group clustering columns in a relatiion, see <a href="#selectWhere">SELECT WHERE</a> clauses.</li><li>Added support for <code>STATIC</code> columns, see <a href="#createTableStatic">static in CREATE TABLE</a>.</li></ul><h3 id="a3.1.4">3.1.4</h3><ul><li><code>CREATE INDEX</code> now allows specifying options when creating CUSTOM indexes (see <a href="#createIndexStmt">CREATE INDEX reference</a>).</li></ul><h3 id="a3.1.3">3.1.3</h3><ul><li>Millisecond precision
formats have been added to the timestamp parser (see <a href="#usingdates">working with dates</a>).</li></ul><h3 id="a3.1.2">3.1.2</h3><ul><li><code>NaN</code> and <code>Infinity</code> has been added as valid float contants. They are now reserved keywords. In the unlikely case you we using them as a column identifier (or keyspace/table one), you will noew need to double quote them (see <a href="#identifiers">quote identifiers</a>).</li></ul><h3 id="a3.1.1">3.1.1</h3><ul><li><code>SELECT</code> statement now allows listing the partition keys (using the <code>DISTINCT</code> modifier). See <a href="https://issues.apache.org/jira/browse/CASSANDRA-4536">CASSANDRA-4536</a>.</li><li>The syntax <code>c IN ?</code> is now supported in <code>WHERE</code> clauses. In that case, the value expected for the bind variable will be a list of whatever type <code>c</code> is.</li><li>It is now possible to use named bind variables (using <code>:name</code> instead of <code>?</code>).</li></ul><h3 id=
"a3.1.0">3.1.0</h3><ul><li><a href="#alterTableStmt">ALTER TABLE</a> <code>DROP</code> option has been reenabled for CQL3 tables and has new semantics now: the space formerly used by dropped columns will now be eventually reclaimed (post-compaction). You should not readd previously dropped columns unless you use timestamps with microsecond precision (see <a href="https://issues.apache.org/jira/browse/CASSANDRA-3919">CASSANDRA-3919</a> for more details).</li><li><code>SELECT</code> statement now supports aliases in select clause. Aliases in WHERE and ORDER BY clauses are not supported. See the “section on select”#selectStmt for details.</li><li><code>CREATE</code> statements for <code>KEYSPACE</code>, <code>TABLE</code> and <code>INDEX</code> now supports an <code>IF NOT EXISTS</code> condition. Similarly, <code>DROP</code> statements support a <code>IF EXISTS</code> condition.</li><li><code>INSERT</code> statements optionally supports a <code>IF NOT EXISTS</code> conditi
on and <code>UPDATE</code> supports <code>IF</code> conditions.</li></ul><h3 id="a3.0.5">3.0.5</h3><ul><li><code>SELECT</code>, <code>UPDATE</code>, and <code>DELETE</code> statements now allow empty <code>IN</code> relations (see <a href="https://issues.apache.org/jira/browse/CASSANDRA-5626">CASSANDRA-5626</a>).</li></ul><h3 id="a3.0.4">3.0.4</h3><ul><li>Updated the syntax for custom <a href="#createIndexStmt">secondary indexes</a>.</li><li>Non-equal condition on the partition key are now never supported, even for ordering partitioner as this was not correct (the order was <strong>not</strong> the one of the type of the partition key). Instead, the <code>token</code> method should always be used for range queries on the partition key (see <a href="#selectWhere">WHERE clauses</a>).</li></ul><h3 id="a3.0.3">3.0.3</h3><ul><li>Support for custom <a href="#createIndexStmt">secondary indexes</a> has been added.</li></ul><h3 id="a3.0.2">3.0.2</h3><ul><li>Type validation for the <a href="#
constants">constants</a> has been fixed. For instance, the implementation used to allow <code>'2'</code> as a valid value for an <code>int</code> column (interpreting it has the equivalent of <code>2</code>), or <code>42</code> as a valid <code>blob</code> value (in which case <code>42</code> was interpreted as an hexadecimal representation of the blob). This is no longer the case, type validation of constants is now more strict. See the <a href="#types">data types</a> section for details on which constant is allowed for which type.</li><li>The type validation fixed of the previous point has lead to the introduction of <a href="#constants">blobs constants</a> to allow inputing blobs. Do note that while inputing blobs as strings constant is still supported by this version (to allow smoother transition to blob constant), it is now deprecated (in particular the <a href="#types">data types</a> section does not list strings constants as valid blobs) and will be removed by a future versio
n. If you were using strings as blobs, you should thus update your client code ASAP to switch blob constants.</li><li>A number of functions to convert native types to blobs have also been introduced. Furthermore the token function is now also allowed in select clauses. See the <a href="#functions">section on functions</a> for details.</li></ul><h3 id="a3.0.1">3.0.1</h3><ul><li><a href="#usingdates">Date strings</a> (and timestamps) are no longer accepted as valid <code>timeuuid</code> values. Doing so was a bug in the sense that date string are not valid <code>timeuuid</code>, and it was thus resulting in <a href="https://issues.apache.org/jira/browse/CASSANDRA-4936">confusing behaviors</a>. However, the following new methods have been added to help working with <code>timeuuid</code>: <code>now</code>, <code>minTimeuuid</code>, <code>maxTimeuuid</code> , <code>dateOf</code> and <code>unixTimestampOf</code>. See the <a href="#usingtimeuuid">section dedicated to these methods</a> for
more detail.</li><li>“Float constants”#constants now support the exponent notation. In other words, <code>4.2E10</code> is now a valid floating point value.</li></ul><h2 id="Versioning">Versioning</h2><p>Versioning of the CQL language adheres to the <a href="http://semver.org">Semantic Versioning</a> guidelines. Versions take the form X.Y.Z where X, Y, and Z are integer values representing major, minor, and patch level respectively. There is no correlation between Cassandra release versions and the CQL language version.</p><table><tr><th>version</th><th>description</th></tr><tr><td>Major </td><td>The major version <em>must</em> be bumped when backward incompatible changes are introduced. This should rarely occur.</td></tr><tr><td>Minor </td><td>Minor version increments occur when new, but backward compatible, functionality is introduced.</td></tr><tr><td>Patch </td><td>The patch version is incremented when bugs are fixed.</td></tr></table></body></html>
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