pgsql: Doc: indexUnchanged is strictly a hint.

pgsql: Doc: indexUnchanged is strictly a hint.

Doc: indexUnchanged is strictly a hint.

Clearly spell out the limitations of aminsert()'s indexUnchanged hinting
mechanism in the index AM documentation.

Oversight in commit 9dc718bd, which added the "logically unchanged
index" hint (which is used to trigger bottom-up index deletion).

Author: Peter Geoghegan 
Reported-By: Tom Lane 
Reviewed-By: Tom Lane 
Discussion: https://postgr.es/m/CAH2-WzmU_BQ=-H9L+bxTSMQBqHMjp1DSwGypvL0gKs+dTOfkKg@mail.gmail.com
Backpatch: 14-, where indexUnchanged hinting was introduced.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/74e5ea1e002f861d499ded6562cab9e769f44781

Modified Files
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doc/src/sgml/indexam.sgml | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)