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Posted to commits@impala.apache.org by as...@apache.org on 2023/03/21 15:30:32 UTC
[impala] branch master updated: IMPALA-11596: [DOCS] Document EXECUTE ROLLBACK functionality
This is an automated email from the ASF dual-hosted git repository.
asherman pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/impala.git
The following commit(s) were added to refs/heads/master by this push:
new b969a1fc6 IMPALA-11596: [DOCS] Document EXECUTE ROLLBACK functionality
b969a1fc6 is described below
commit b969a1fc6ad2f89c36f0b644dd9070259b9ad89b
Author: Andrew Sherman <as...@cloudera.com>
AuthorDate: Wed Mar 8 12:57:58 2023 -0800
IMPALA-11596: [DOCS] Document EXECUTE ROLLBACK functionality
Since IMPALA-11482 Impala supports the 'Alter Table Execute Rollback'
statement for Iceberg tables. Update the docs to cover this change.
The section on DESCRIBE HSTORY is expanded to include the output
columns, as this information is relevant to EXECUTE ROLLBACK.
The section on Cloning Iceberg tables is moved so that the sections
concerned with table history are adjacent.
TESTING:
- Built docs locally.
Change-Id: I0e1690378e560197263c49f468618b1ded922df3
Reviewed-on: http://gerrit.cloudera.org:8080/19606
Tested-by: Impala Public Jenkins <im...@cloudera.com>
Reviewed-by: Noemi Pap-Takacs <np...@cloudera.com>
Reviewed-by: Zoltan Borok-Nagy <bo...@cloudera.com>
---
docs/topics/impala_iceberg.xml | 63 +++++++++++++++++++++++++++++++++++-------
1 file changed, 53 insertions(+), 10 deletions(-)
diff --git a/docs/topics/impala_iceberg.xml b/docs/topics/impala_iceberg.xml
index 62abca615..df66d5a0b 100644
--- a/docs/topics/impala_iceberg.xml
+++ b/docs/topics/impala_iceberg.xml
@@ -139,7 +139,7 @@ TBLPROPERTIES('iceberg.catalog'='hadoop.catalog',
<li>
Alternatively, you can also use custom catalogs to use existing tables. It means you need to define
your catalog in hive-site.xml.
- The adventage of this method is that other engines are more likely to be able to interact with this table.
+ The advantage of this method is that other engines are more likely to be able to interact with this table.
To globally register different catalogs, set the following Hadoop configurations:
<table rowsep="1" colsep="1" id="iceberg_custom_catalogs">
<tgroup cols="2">
@@ -238,7 +238,7 @@ CREATE TABLE ice_ctas_part_spec PARTITIONED BY SPEC (truncate(3, s)) STORED AS I
<conbody>
<p>
- You can get information about the supported Iceberg data tyeps in
+ You can get information about the supported Iceberg data types in
<xref href="https://iceberg.apache.org/docs/latest/schemas/" scope="external" format="html">
the Iceberg spec</xref>.
</p>
@@ -497,6 +497,16 @@ DESCRIBE HISTORY ice_t FROM now() - interval 5 days;
DESCRIBE HISTORY ice_t BETWEEN '2022-01-04 10:00:00' AND '2022-01-05 10:00:00';
</codeblock>
</p>
+ <p>
+ The output of the <codeph>DESCRIBE HISTORY</codeph> statement is formed
+ of the following columns:
+ <ul>
+ <li><codeph>creation_time</codeph>: the snapshot's creation timestamp.</li>
+ <li><codeph>snapshot_id</codeph>: the snapshot's ID or null.</li>
+ <li><codeph>parent_id</codeph>: the snapshot's parent ID or null.</li>
+ <li><codeph>is_current_ancestor</codeph>: TRUE if the snapshot is a current ancestor of the table.</li>
+ </ul>
+ </p>
<p rev="4.3.0 IMPALA-10893">
Please note that time travel queries are executed using the old schema of the table
@@ -508,20 +518,35 @@ DESCRIBE HISTORY ice_t BETWEEN '2022-01-04 10:00:00' AND '2022-01-05 10:00:00';
</conbody>
</concept>
- <concept id="iceberg_table_cloning">
- <title>Cloning Iceberg tables (LIKE clause)</title>
+ <concept id="iceberg_execute_rollback">
+ <title>Rolling Iceberg tables back to a previous state</title>
<conbody>
<p>
- Use <codeph>CREATE TABLE ... LIKE ...</codeph> to create an empty Iceberg table
- based on the definition of another Iceberg table, including any column attributes in
- the original table:
+ Iceberg table modifications cause new table snapshots to be created;
+ these snapshots represent an earlier version of the table.
+ The <codeph>ALTER TABLE [<varname>db_name</varname>.]<varname>table_name</varname> EXECUTE ROLLBACK</codeph>
+ statement can be used to roll back the table to a previous snapshot.
+ </p>
+
+ <p>
+ For example, to roll the table back to the snapshot id <codeph>123456</codeph> use:
+ <codeblock>
+ALTER TABLE ice_tbl EXECUTE ROLLBACK(123456);
+ </codeblock>
+ To roll the table back to the most recent (newest) snapshot
+ that has a creation timestamp that is older than the timestamp '2022-01-04 10:00:00' use:
<codeblock>
-CREATE TABLE new_ice_tbl LIKE orig_ice_tbl;
+ALTER TABLE ice_tbl EXECUTE ROLLBACK('2022-01-04 10:00:00');
</codeblock>
+ The timestamp is evaluated using the Timezone for the current session.
</p>
+
<p>
- Because of the Data Types of Iceberg and Impala do not correspond one by one, Impala
- can only clone between Iceberg tables.
+ It is only possible to roll back to a snapshot that is a current ancestor of the table.
+ </p>
+ <p>
+ When a table is rolled back to a snapshot, a new snapshot is
+ created with the same snapshot id, but with a new creation timestamp.
</p>
</conbody>
</concept>
@@ -558,6 +583,24 @@ ALTER TABLE ice_tbl EXECUTE expire_snapshots(now() - interval 5 days);
</conbody>
</concept>
+ <concept id="iceberg_table_cloning">
+ <title>Cloning Iceberg tables (LIKE clause)</title>
+ <conbody>
+ <p>
+ Use <codeph>CREATE TABLE ... LIKE ...</codeph> to create an empty Iceberg table
+ based on the definition of another Iceberg table, including any column attributes in
+ the original table:
+ <codeblock>
+ CREATE TABLE new_ice_tbl LIKE orig_ice_tbl;
+ </codeblock>
+ </p>
+ <p>
+ Because of the Data Types of Iceberg and Impala do not correspond one by one, Impala
+ can only clone between Iceberg tables.
+ </p>
+ </conbody>
+ </concept>
+
<concept id="iceberg_table_properties">
<title>Iceberg table properties</title>
<conbody>