[6X] Add distributed snapshot support to pg_export_snapshot #13470
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soumyadeep2007
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May 12, 2022
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LGTM! It would be nice if you can follow the following backport format for the commit messages:
Backport commit messages should be of the following form:
Clean cherry-picks where there is no conflict resolution (tip: run with -x)
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<original commit message body>
(cherry-picked from commit <SHA of **merged commit** in 7x>)
OR
Unclean cherry-picks where conflict resolution was necessary:
<original commit message title>
Backported from commit <SHA of **merged commit** in 7x>
Conflict resolution:
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Original commit message follows:
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This commit ensures that we use setDistributedTransactionContext() in sinval.c, the only place where we weren't. Also, this commit ensures that we log the act of setting the context, while respecting the debug_print_full_dtm GUC. (cherry-picked from commit 2fafef9, minor changes to formatting)
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This commit adds distributed snapshot metadata when exporting and importing snapshots. Calling `select pg_export_snapshot()` from the QD will write the following fields to the snapshot file in `pg_snapshots` in the coordinator data directory. ``` dsxminall dsid dsxmin dsxmax dscnt dsxip ``` When a snapshot is imported via SET TRANSACTION SNAPSHOT from the QD, subsequent queries will have the distributed snapshot metadata dispatched to the QEs. This enables cluster-wide data visibility consistency. (cherry picked from commit eeb37b9, parseDistributedXidFromText function not backported)
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Backport from #13201
Add distributed snapshot support to pg_export_snapshot
pg_export_snapshot now exports distributed snapshot metadata, enabling cluster-wide data visibility consistency via
SET TRANSACTION SNAPSHOTCalling
select pg_export_snapshot()from the QD will write thefollowing fields to the snapshot file in
pg_snapshotsin thecoordinator data directory.
When a snapshot is imported via SET TRANSACTION SNAPSHOT from the QD, subsequent
queries will have the distributed snapshot metadata dispatched to the QEs.
Reference: https://groups.google.com/a/greenplum.org/g/gpdb-dev/c/C6cY8yIbcps