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hash as an search key and hash collision - Mailing list pgsql-hackers

From	Andy Fan
Subject	hash as an search key and hash collision
Date	June 19, 2020 11:24:01
Msg-id	CAKU4AWrhg3=fNnzc+wzO-0Or7Ot3hiKUu8N4draJ=6ZbqWJbBA@mail.gmail.com Whole thread Raw
Responses	Re: hash as an search key and hash collision (Tomas Vondra <tomas.vondra@2ndquadrant.com>)
List	pgsql-hackers

I want to maintain an internal table which the primary key is sql_text and

planstmt::text, it is efficient since it both may be very long. So a general

idea is to use sql_hash_value and plan_hash_value. Then we have to

handle the hash collision case. However I checked the codes both in sr_plans[1]

and pg_stat_statements[2], both of them didn't handle such cases, IIUC. so

how can I understand this situation?

[1] https://github.com/postgrespro/sr_plan/blob/41d96bf136ec072dac77dddf8d9765bba39190ff/sr_plan.c#L383

[2] https://github.com/postgres/postgres/blob/master/contrib/pg_stat_statements/pg_stat_statements.c#L154

--

Best Regards

Andy Fan

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