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https://issues.apache.org/jira/browse/HIVE-26168?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Harshit Gupta reassigned HIVE-26168:
------------------------------------
Assignee: Harshit Gupta
> EXPLAIN DDL command output is not deterministic
> ------------------------------------------------
>
> Key: HIVE-26168
> URL: https://issues.apache.org/jira/browse/HIVE-26168
> Project: Hive
> Issue Type: Bug
> Components: HiveServer2
> Reporter: Stamatis Zampetakis
> Assignee: Harshit Gupta
> Priority: Minor
>
> The EXPLAIN DDL command (HIVE-24596) can be used to recreate the schema for a
> given query in order to debug planner issues. This is achieved by fetching
> information from the metastore and outputting series of DDL commands.
> The output commands though may appear in different order among runs since
> there is no mechanism to enforce an explicit order.
> Consider for instance the following scenario.
> {code:sql}
> CREATE TABLE customer
> (
> `c_custkey` bigint,
> `c_name` string,
> `c_address` string
> );
> INSERT INTO customer VALUES (1, 'Bob', '12 avenue Mansart'), (2, 'Alice', '24
> avenue Mansart');
> EXPLAIN DDL SELECT c_custkey FROM customer WHERE c_name = 'Bob';
> {code}
> +Result 1+
> {noformat}
> ALTER TABLE default.customer UPDATE STATISTICS
> SET('numRows'='2','rawDataSize'='48' );
> ALTER TABLE default.customer UPDATE STATISTICS FOR COLUMN c_address
> SET('avgColLen'='17.0','maxColLen'='17','numNulls'='0','numDVs'='2' );
> -- BIT VECTORS PRESENT FOR default.customer FOR COLUMN c_address BUT THEY ARE
> NOT SUPPORTED YET. THE BASE64 VALUE FOR THE BITVECTOR IS SExMoAICwbec/QPAjtBF
> ALTER TABLE default.customer UPDATE STATISTICS FOR COLUMN c_custkey
> SET('lowValue'='1','highValue'='2','numNulls'='0','numDVs'='2' );
> -- BIT VECTORS PRESENT FOR default.customer FOR COLUMN c_custkey BUT THEY ARE
> NOT SUPPORTED YET. THE BASE64 VALUE FOR THE BITVECTOR IS SExMoAICwfO+SIOOofED
> ALTER TABLE default.customer UPDATE STATISTICS FOR COLUMN c_name
> SET('avgColLen'='4.0','maxColLen'='5','numNulls'='0','numDVs'='2' );
> -- BIT VECTORS PRESENT FOR default.customer FOR COLUMN c_name BUT THEY ARE
> NOT SUPPORTED YET. THE BASE64 VALUE FOR THE BITVECTOR IS
> SExMoAIChJLg1AGD1aCNBg==
> {noformat}
> +Result 2+
> {noformat}
> ALTER TABLE default.customer UPDATE STATISTICS
> SET('numRows'='2','rawDataSize'='48' );
> ALTER TABLE default.customer UPDATE STATISTICS FOR COLUMN c_custkey
> SET('lowValue'='1','highValue'='2','numNulls'='0','numDVs'='2' );
> -- BIT VECTORS PRESENT FOR default.customer FOR COLUMN c_custkey BUT THEY ARE
> NOT SUPPORTED YET. THE BASE64 VALUE FOR THE BITVECTOR IS SExMoAICwfO+SIOOofED
> ALTER TABLE default.customer UPDATE STATISTICS FOR COLUMN c_address
> SET('avgColLen'='17.0','maxColLen'='17','numNulls'='0','numDVs'='2' );
> -- BIT VECTORS PRESENT FOR default.customer FOR COLUMN c_address BUT THEY ARE
> NOT SUPPORTED YET. THE BASE64 VALUE FOR THE BITVECTOR IS SExMoAICwbec/QPAjtBF
>
> ALTER TABLE default.customer UPDATE STATISTICS FOR COLUMN c_name
> SET('avgColLen'='4.0','maxColLen'='5','numNulls'='0','numDVs'='2' );
> -- BIT VECTORS PRESENT FOR default.customer FOR COLUMN c_name BUT THEY ARE
> NOT SUPPORTED YET. THE BASE64 VALUE FOR THE BITVECTOR IS
> SExMoAIChJLg1AGD1aCNBg==
> {noformat}
> The two results are equivalent but the statements appear in a different
> order. This is not a big issue cause the results remain correct but it may
> lead to test flakiness so it might be worth addressing.
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