On Mon, Mar 3, 2025 at 4:45 PM jian he <jian.universal...@gmail.com> wrote: > > looking at DefineRelation comments: > * We can set the atthasdef flags now in the tuple descriptor; this just > * saves StoreAttrDefault from having to do an immediate update of the > * pg_attribute rows. > this seems not right? > DefineRelation->heap_create_with_catalog->heap_create->RelationBuildLocalRelation->CreateTupleDescCopy > don't copy atthasdef. > RelationBuildLocalRelation later didn't touch atthasdef. > populate_compact_attribute didn't touch atthasdef. > so StoreAttrDefault has to update that pg_attribute row. > CREATE TABLE (COLUMN x DEFAULT y): for each (Relation rel, AttrNumber attnum), we can enter StoreAttrDefault once. Also for the above quoted reason, in DefineRelation, we didn't change pg_attribute.atthasdef before entering StoreAttrDefault.
ALTER TABLE ALTER COLUMN SET/DROP DEFAULT: in ATExecColumnDefault will first do RemoveAttrDefault, then re add the default expression. In this case, in StoreAttrDefault: attStruct->atthasdef will be false. overall, i think DefineRelation about StoreAttrDefault comments can be removed. and StoreAttrDefault, "if (!attStruct->atthasdef)" part logic can also be changed. The attached is the minor change I came up with, based on v3-0001 and v3-0002.
v3-0001-minor-refactoring-DefineRelation-StoreAttrDefa.no-cfbot
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