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Generated columns

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This is an SQL-standard feature that allows creating columns that are
computed from expressions rather than assigned, similar to a view or
materialized view but on a column basis.

This implements one kind of generated column: stored (computed on
write).  Another kind, virtual (computed on read), is planned for the
future, and some room is left for it.

Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/b151f851-4019-bdb1-699e-ebab07d2f40a@2ndquadrant.com
This commit is contained in:
Peter Eisentraut
2019-03-30 08:13:09 +01:00
parent 6b8b5364dd
commit fc22b6623b
84 changed files with 3067 additions and 157 deletions
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4
src/backend/utils/cache/relcache.c vendored
View File

@@ -515,6 +515,7 @@ RelationBuildTupleDesc(Relation relation)
constr = (TupleConstr *) MemoryContextAlloc(CacheMemoryContext,
sizeof(TupleConstr));
constr->has_not_null = false;
constr->has_generated_stored = false;
/*
* Form a scan key that selects only user attributes (attnum > 0).
@@ -567,6 +568,8 @@ RelationBuildTupleDesc(Relation relation)
/* Update constraint/default info */
if (attp->attnotnull)
constr->has_not_null = true;
if (attp->attgenerated == ATTRIBUTE_GENERATED_STORED)
constr->has_generated_stored = true;
/* If the column has a default, fill it into the attrdef array */
if (attp->atthasdef)
@@ -3281,6 +3284,7 @@ RelationBuildLocalRelation(const char *relname,
Form_pg_attribute datt = TupleDescAttr(rel->rd_att, i);
datt->attidentity = satt->attidentity;
datt->attgenerated = satt->attgenerated;
datt->attnotnull = satt->attnotnull;
has_not_null |= satt->attnotnull;
}