On 3/25/22 13:30, Tom Lane wrote:
Thank you for the indulgence! I clearly owe you (another) one.Rob Sargent <robjsargent@xxxxxxxxx> writes:As far as the comparison behavior goes, psql's parser strips comments that start with double dashes, for $obscure_reasons.That story aught to be worth a $beer or twoHmm. The original reasoning is lost in the mists of time; I dug in our git history and traced the behavior as far back as a45195a19 of 1999-11-04, but I'll bet a nickel that Peter doesn't remember exactly why he did that. But I can show you why I gave up on removing the behavior: it's an important part of psql's strategy of discarding leading whitespace before a query. Our regression test scripts are full of cases like -- comments here SELECT intentionally-wrong-query; and what they're expecting to get from that is output like ERROR: column "intentionally" does not exist LINE 1: SELECT intentionally-wrong-query; ^ When I changed psql's parser to not remove comments, that output suddenly changed to say "LINE 3:", because now the query string sent to the server included the "-- comments here" line as well as the blank line after it. While we could have changed all the expected output, or changed how the server counts lines within a query, we concluded that this would confuse too many people and break too many applications; so we left it alone. (As of v15, psql will send -- comments that begin *after* the first non-whitespace token of a query [1]. But leading comments and whitespace will still get stripped.) regards, tom lane [1] https://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=83884682f4df96184549b91869a1cf79dafb4f94
