Not entirely.
Per <http://www.postgresql.org/docs/7.4/static/functions-string.html>, btrim is documented as taking two arguments. There is a single-argument version that exists that trims whitespace if only the first argument is given (i.e., the characters to trim are omitted). This latter version is nowhere documented as far as I can tell.
I'm also curious why, despite its place in the ANSI standard, \df seems to reveal no information about trim.
-tfo
-- Thomas F. O'Connell Co-Founder, Information Architect Sitening, LLC http://www.sitening.com/ 110 30th Avenue North, Suite 6 Nashville, TN 37203-6320 615-260-0005
On Nov 27, 2004, at 9:23 PM, Bruce Momjian wrote:
Thomas F.O'Connell wrote:I was just wondering why the btrim syntax that takes only a single argument is not documented in 9.4 in the documentation (I checked both 7.4 and 8.0 docs).
This is in a 7.4.5 installation:
pg=# \df btrim List of functions Result data type | Schema | Name | Argument data types ------------------+------------+-------+--------------------- bytea | pg_catalog | btrim | bytea, bytea text | pg_catalog | btrim | text text | pg_catalog | btrim | text, text (3 rows)
Is it ever documented anywhere that the single-argument version of btrim can be used to remove whitespace from the left and right of a given string? Is this version not supposed to be user-facing for some reason?
Also, in this post:
http://archives.postgresql.org/pgsql-sql/2002-01/msg00053.php
Bruce sort of explains that TRIM is an ANSI word but doesn't fully explain why it doesn't show up in a \df listing:
pg=# \df trim List of functions Result data type | Schema | Name | Argument data types ------------------+--------+------+--------------------- (0 rows)
This one's more a curiosity thing.
Because TRIM is an ANSI standard, we document TRIM (BOTH, ...) but not btrim. The parser does the translation:
| TRIM '(' BOTH trim_list ')' { /* various trim expressions are defined in SQL92 * - thomas 1997-07-19 */ FuncCall *n = makeNode(FuncCall); n->funcname = SystemFuncName("btrim"); n->args = $4; n->agg_star = FALSE; n->agg_distinct = FALSE; $$ = (Node *)n;
Does that answer your questions?
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