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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2022-08-17 11:12:35 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2022-08-17 11:12:35 -0400 |
| commit | efd0c16becbf45e3b0215e124fde75fee8fcbce4 (patch) | |
| tree | 4583c8e845ce18ae4a6c6b4c008a4989c514b3cb /src/backend/commands/typecmds.c | |
| parent | 4a319fce7671ffbe2a730f79529b7a2ef3794d41 (diff) | |
| download | postgresql-efd0c16becbf45e3b0215e124fde75fee8fcbce4.tar.gz postgresql-efd0c16becbf45e3b0215e124fde75fee8fcbce4.zip | |
Avoid using list_length() to test for empty list.
The standard way to check for list emptiness is to compare the
List pointer to NIL; our list code goes out of its way to ensure
that that is the only representation of an empty list. (An
acceptable alternative is a plain boolean test for non-null
pointer, but explicit mention of NIL is usually preferable.)
Various places didn't get that memo and expressed the condition
with list_length(), which might not be so bad except that there
were such a variety of ways to check it exactly: equal to zero,
less than or equal to zero, less than one, yadda yadda. In the
name of code readability, let's standardize all those spellings
as "list == NIL" or "list != NIL". (There's probably some
microscopic efficiency gain too, though few of these look to be
at all performance-critical.)
A very small number of cases were left as-is because they seemed
more consistent with other adjacent list_length tests that way.
Peter Smith, with bikeshedding from a number of us
Discussion: https://postgr.es/m/CAHut+PtQYe+ENX5KrONMfugf0q6NHg4hR5dAhqEXEc2eefFeig@mail.gmail.com
Diffstat (limited to 'src/backend/commands/typecmds.c')
| -rw-r--r-- | src/backend/commands/typecmds.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c index d0d87a1184a..33b64fd2793 100644 --- a/src/backend/commands/typecmds.c +++ b/src/backend/commands/typecmds.c @@ -3503,7 +3503,7 @@ domainAddConstraint(Oid domainOid, Oid domainNamespace, Oid baseTypeOid, * Domains don't allow variables (this is probably dead code now that * add_missing_from is history, but let's be sure). */ - if (list_length(pstate->p_rtable) != 0 || + if (pstate->p_rtable != NIL || contain_var_clause(expr)) ereport(ERROR, (errcode(ERRCODE_INVALID_COLUMN_REFERENCE), |