[jira] [Updated] (CASSANDRA-19874) Function inference maybe unable to infer the correct function or chooses one for a smaller type

["David Capwell (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-19874?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

David Capwell updated CASSANDRA-19874:
--------------------------------------
    Fix Version/s: 5.x

> Function inference maybe unable to infer the correct function or chooses one for a smaller type
> -----------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-19874
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-19874
>             Project: Cassandra
>          Issue Type: Bug
>          Components: CQL/Interpreter
>            Reporter: David Capwell
>            Priority: Normal
>             Fix For: 5.x
>
>
> Here are 2 numeric examples where function inference doesn’t do the right thing
> 1) varint
> Case 1: Wrong Bytes
> {code}
> BigInteger pk = BigInteger.valueOf(-42 + -42);
> BigInteger ck = BigInteger.valueOf(42 + 42);
> BigInteger v = BigInteger.valueOf(-8200 + -16990);
> createTable("CREATE TABLE %s(pk varint, ck varint, v varint, PRIMARY KEY(pk, ck))");
> execute("INSERT INTO %s(pk, ck, v) VALUES (-42 + -42, 42 + 42, -8200 + -16990)");
> assertRows(execute("SELECT * FROM %s"),
>            row(pk, ck, v));
> assertRows(execute("SELECT * FROM %s WHERE pk=?", pk),
>            row(pk, ck, v));
> assertRows(execute("SELECT * FROM %s WHERE pk=? AND ck=?", pk, ck),
>            row(pk, ck, v));
> {code}
> This fails with
> {code}
> java.lang.AssertionError: Got less rows than expected. Expected 1 but got 0
> {code}
> The reason is that the "system._add: (int, int) -> int” function works for ints rather than varint, which means the bytes created do not match the bytes that a varint would have created!
> In the example of -42 + -42 we get -84 which is a single byte for varint and 4 bytes for int.  Since the bytes don’t match partition/clustering equality does not match!
> Case 2: Overflow
> {code}
> BigInteger pk = BigInteger.valueOf(59463118).multiply(BigInteger.valueOf(-2171));
> BigInteger ck = pk;
> BigInteger v = pk;
> createTable("CREATE TABLE %s(pk varint, ck varint, v varint, PRIMARY KEY(pk, ck))");
> execute("INSERT INTO %s(pk, ck, v) VALUES (59463118 * -2171, 59463118 * -2171, 59463118 * -2171)");
> assertRows(execute("SELECT * FROM %s"),
>            row(pk, ck, v));
> {code}
> This fails with
> {code}
> java.lang.AssertionError: Invalid value for row 0 column 0 (pk of type varint), expected <-129094429178> but got <-245410298>
> Invalid value for row 0 column 1 (ck of type varint), expected <-129094429178> but got <-245410298>
> Invalid value for row 0 column 2 (v of type varint), expected <-129094429178> but got <-245410298>
> {code}
> The reason for this is the same as above, we selected “system._multiply: (int, int) -> int”, and if you do 59463118 * -2171 as an int it overflows and produces -245410298.  If you instead upgrade the 2 ints to a BigInteger and then do the multiple you get -129094429178!
> This isn’t a problem for other databases, here is an example with sqlite
> {code}
> sqlite> create table foo2(pk varint);
> sqlite> insert into foo2(pk) values (59463118 * -2171);
> sqlite> select * from foo2;
>    pk = -129094429178
> {code}
> 2) smallint
> {code}
> createTable("CREATE TABLE %s(pk smallint, ck smallint, v smallint, PRIMARY KEY(pk, ck)) WITH CLUSTERING ORDER BY (ck DESC)");
> execute("INSERT INTO %s(pk, ck, v) VALUES (-42 + -42, 42 + 42, -42 + 42)");
> {code}
> Here the function selection fails as it can’t find a match
> {code}
> org.apache.cassandra.exceptions.InvalidRequestException: Ambiguous '+' operation with args 42 and 42: use type hint to disambiguate, example '(int) ?'
> 	at org.apache.cassandra.cql3.statements.RequestValidations.invalidRequest(RequestValidations.java:370)
> 	at org.apache.cassandra.cql3.functions.FunctionResolver.pickBestMatch(FunctionResolver.java:179)
> 	at org.apache.cassandra.cql3.functions.FunctionResolver.get(FunctionResolver.java:87)
> 	at org.apache.cassandra.cql3.functions.FunctionCall$Raw.prepare(FunctionCall.java:154)
> {code}
> The reason here is similar to the above… we think that the numbers “-42”, and “42” are “int” type rather than “smallint” and we don’t find a function to pick up! 
> If instead you just did 
> {code} 
> INSERT INTO %s(pk, ck, v) VALUES(-42, 42, 42)
> {code} 
> We would then be able to infer that these are “smallint” rather than upcasting them to “int”.
> This isn’t a problem for other databases, here is an example from sqlite
> {code}
> sqlite> create table foo(pk smallint);
> sqlite> insert into foo(pk) values (-42 + -42);
> sqlite> select * from foo;
>    pk = -84
> {code}



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