E.158. Version 7.4.20

Fix conversions between ISO-8859-5 and other encodings to handle Cyrillic « Yo » characters (e and E with two dots) (Sergey Burladyan)

Fix a few datatype input functions that were allowing unused bytes in their results to contain uninitialized, unpredictable values (Tom)

This could lead to failures in which two apparently identical literal values were not seen as equal, resulting in the parser complaining about unmatched ORDER BY and DISTINCT expressions.

Fix a corner case in regular-expression substring matching (substring(string from pattern)) (Tom)

The problem occurs when there is a match to the pattern overall but the user has specified a parenthesized subexpression and that subexpression hasn't got a match. An example is substring('foo' from 'foo(bar)?'). This should return NULL, since (bar) isn't matched, but it was mistakenly returning the whole-pattern match instead (ie, foo).

Fix incorrect result from ecpg's PGTYPEStimestamp_sub() function (Michael)

Fix DatumGetBool macro to not fail with gcc 4.3 (Tom)

This problem affects « old style » (V0) C functions that return boolean. The fix is already in 8.3, but the need to back-patch it was not realized at the time.

Fix longstanding LISTEN/NOTIFY race condition (Tom)

In rare cases a session that had just executed a LISTEN might not get a notification, even though one would be expected because the concurrent transaction executing NOTIFY was observed to commit later.

A side effect of the fix is that a transaction that has executed a not-yet-committed LISTEN command will not see any row in pg_listener for the LISTEN, should it choose to look; formerly it would have. This behavior was never documented one way or the other, but it is possible that some applications depend on the old behavior.

Fix display of constant expressions in ORDER BY and GROUP BY (Tom)

An explictly casted constant would be shown incorrectly. This could for example lead to corruption of a view definition during dump and reload.

Fix libpq to handle NOTICE messages correctly during COPY OUT (Tom)

This failure has only been observed to occur when a user-defined datatype's output routine issues a NOTICE, but there is no guarantee it couldn't happen due to other causes.