Postpone some stuff out of ExecInitModifyTable

Enterprise / PostgreSQL - Tom Lane [] - 6 April 2021 19:57 UTC

Arrange to do some things on-demand, rather than immediately during executor startup, because there's a fair chance of never having to do them at all:

- Don't open result relations' indexes until needed.

- Don't initialize partition tuple routing, nor the child-to-root tuple conversion map, until needed.

This wins in UPDATEs on partitioned tables when only some of the partitions will actually receive updates; with larger partition counts the savings is quite noticeable. Also, we can remove some sketchy heuristics in ExecInitModifyTable about whether to set up tuple routing.

Also, remove execPartition.c's private hash table tracking which partitions were already opened by the ModifyTable node. Instead use the hash added to ModifyTable itself by commit 86dc90056.

To allow lazy computation of the conversion maps, we now set ri_RootResultRelInfo in all child ResultRelInfos. We formerly set it only in some, not terribly well-defined, cases. This has user-visible side effects in that now more error messages refer to the root relation instead of some partition (and provide error data in the root's column order, too). It looks to me like this is a strict improvement in consistency, so I don't have a problem with the output changes visible in this commit.

Extracted from a larger patch, which seemed to me to be too messy to push in one commit.

Amit Langote, reviewed at different times by Heikki Linnakangas and myself


c5b7ba4e67 Postpone some stuff out of ExecInitModifyTable.
src/backend/commands/copyfrom.c | 2 +-
src/backend/commands/trigger.c | 2 +-
src/backend/executor/execMain.c | 8 +
src/backend/executor/execPartition.c | 183 ++++++-----------------
src/backend/executor/execUtils.c | 26 ++++
src/backend/executor/nodeModifyTable.c | 247 ++++++++++++++++---------------
src/backend/replication/logical/worker.c | 2 +-
src/include/executor/execPartition.h | 1 -
src/include/executor/executor.h | 9 +-
src/include/nodes/execnodes.h | 6 +-
src/test/regress/expected/inherit.out | 2 +-
src/test/regress/expected/privileges.out | 2 +-
src/test/regress/expected/update.out | 12 +-
13 files changed, 235 insertions(+), 267 deletions(-)


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