Tom Lane 65a3ff8f1b Doc: improve user docs and code comments about EXISTS(SELECT * ...). ... Point out that Postgres automatically optimizes away the target list of an EXISTS' subquery, except in weird cases such as target lists containing set-returning functions. Thus, both common conventions EXISTS(SELECT * FROM ...) and EXISTS(SELECT 1 FROM ...) are overhead-free and there's little reason to prefer one over the other. In the code comments, mention that the SQL spec says that EXISTS(SELECT * FROM ...) should be interpreted as EXISTS(SELECT some-literal FROM ...), but we don't choose to do it exactly that way. Author: Peter Eisentraut <peter@eisentraut.org> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/9b301c70-3909-4f0f-98ca-9e3c4d142f3e@eisentraut.org		2026-02-27 15:20:16 -05:00
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src	Doc: improve user docs and code comments about EXISTS(SELECT * ...).	2026-02-27 15:20:16 -05:00
KNOWN_BUGS
Makefile	Remove distprep	2023-11-06 15:18:04 +01:00
MISSING_FEATURES
TODO	Change documentation references to PG website to use https: not http:	2017-05-20 21:50:47 -04:00