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Record dependencies of a cast on other casts that it requires.

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When creating a cast that uses a conversion function, we've
historically allowed the input and result types to be
binary-compatible with the function's input and result types,
rather than necessarily being identical.  This means that the new
cast is logically dependent on the binary-compatible cast or casts
that it references: if those are defined by pg_cast entries, and you
try to restore the new cast without having defined them, it'll fail.
Hence, we should make pg_depend entries to record these dependencies
so that pg_dump knows that there is an ordering requirement.

This is not the only place where we allow such shortcuts; aggregate
functions for example are similarly lax, and in principle should gain
similar dependencies.  However, for now it seems sufficient to fix
the cast-versus-cast case, as pg_dump's other ordering heuristics
should keep it out of trouble for other object types.

Per report from David Turoň; thanks also to Robert Haas for
preliminary investigation.  I considered back-patching, but
seeing that this issue has existed for many years without
previous reports, it's not clear it's worth the trouble.
Moreover, back-patching wouldn't be enough to ensure that the
new pg_depend entries exist in existing databases anyway.

Discussion: https://postgr.es/m/OF0A160F3E.578B15D1-ONC12588DA.003E4857-C12588DA.0045A428@notes.linuxbox.cz
This commit is contained in:
Tom Lane
2022-10-17 14:02:05 -04:00
parent 797e313dc9
commit 8272749e8c
9 changed files with 111 additions and 9 deletions
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14
src/backend/commands/functioncmds.c
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@ -1526,6 +1526,8 @@ CreateCast(CreateCastStmt *stmt)
char sourcetyptype;
char targettyptype;
Oid funcid;
Oid incastid = InvalidOid;
Oid outcastid = InvalidOid;
int nargs;
char castcontext;
char castmethod;
@ -1603,7 +1605,9 @@ CreateCast(CreateCastStmt *stmt)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("cast function must take one to three arguments")));
if (!IsBinaryCoercible(sourcetypeid, procstruct->proargtypes.values[0]))
if (!IsBinaryCoercibleWithCast(sourcetypeid,
procstruct->proargtypes.values[0],
&incastid))
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("argument of cast function must match or be binary-coercible from source data type")));
@ -1617,7 +1621,9 @@ CreateCast(CreateCastStmt *stmt)
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("third argument of cast function must be type %s",
"boolean")));
if (!IsBinaryCoercible(procstruct->prorettype, targettypeid))
if (!IsBinaryCoercibleWithCast(procstruct->prorettype,
targettypeid,
&outcastid))
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("return data type of cast function must match or be binary-coercible to target data type")));
@ -1756,8 +1762,8 @@ CreateCast(CreateCastStmt *stmt)
break;
}
myself = CastCreate(sourcetypeid, targettypeid, funcid, castcontext,
castmethod, DEPENDENCY_NORMAL);
myself = CastCreate(sourcetypeid, targettypeid, funcid, incastid, outcastid,
castcontext, castmethod, DEPENDENCY_NORMAL);
return myself;
}