Revise attribute handling code on partition creation

Enterprise / PostgreSQL - Alvaro Herrera [] - 8 November 2018 19:22 EST

The original code to propagate NOT NULL and default expressions specified when creating a partition was mostly copy-pasted from typed-tables creation, but not being a great match it contained some duplicity, inefficiency and bugs.

This commit fixes the bug that NOT NULL constraints declared in the parent table would not be honored in the partition. One reported issue that is not fixed is that a DEFAULT declared in the child is not used when inserting through the parent. That would amount to a behavioral change that's better not back-patched.

This rewrite makes the code simpler:

1. instead of checking for duplicate column names in its own block, reuse the original one that already did that;

2. instead of concatenating the list of columns from parent and the one declared in the partition and scanning the result to (incorrectly) propagate defaults and not-null constraints, just scan the latter searching the former for a match, and merging sensibly. This works because we know the list in the parent is already correct and there can only be one parent.

This rewrite makes ColumnDef->is_from_parent unused, so it's removed on branch master; on released branches, it's kept as an unused field in order not to cause ABI incompatibilities.

This commit also adds a test case for creating partitions with collations mismatching that on the parent table, something that is closely related to the code being patched. No code change is introduced though, since that'd be a behavior change that could break some (broken) working applications.

Amit Langote wrote a less invasive fix for the original NOT NULL/defaults bug, but while I kept the tests he added, I ended up not using his original code. Ashutosh Bapat reviewed Amit's fix. Amit reviewed mine.

Author: Álvaro Herrera, Amit Langote

705d433fd5 Revise attribute handling code on partition creation
src/backend/commands/sequence.c | 1 -
src/backend/commands/tablecmds.c | 99 ++++++++++++++----------------
src/backend/nodes/copyfuncs.c | 1 -
src/backend/nodes/equalfuncs.c | 1 -
src/backend/nodes/makefuncs.c | 1 -
src/backend/nodes/outfuncs.c | 1 -
src/backend/parser/gram.y | 4 --
src/backend/parser/parse_utilcmd.c | 2 -
src/include/nodes/parsenodes.h | 1 -
src/test/regress/expected/create_table.out | 26 ++++++++
src/test/regress/sql/create_table.sql | 19 ++++++
11 files changed, 91 insertions(+), 65 deletions(-)


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