| From: | Ying Lu <ying_lu(at)cs(dot)concordia(dot)ca> |
|---|---|
| To: | pgsql-general(at)postgresql(dot)org |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | "Hash index" vs. "b-tree index" (PostgreSQL 8.0) |
| Date: | 2005-05-09 13:40:35 |
| Message-ID: | 427F6853.90308@cs.concordia.ca |
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| Thread: | |
| Lists: | pgsql-general pgsql-performance |
Greetings,
We are working on speeding up the queries by creating indexes. We have
queries with searching criteria such as "select ... where *col1='...'*".
This is a simple query with only "=" operation. As a result I setup hash
index on column "col1". While, in postgreSQL 8 doc, it is wirttern:
*Note: * Testing has shown PostgreSQL's hash indexes to perform no
better than B-tree indexes, and the index size and build time for hash
indexes is much worse. For these reasons, hash index use is presently
discouraged.
May I know for simple "=" operation query, for "Hash index" vs. "B-tree"
index, which can provide better performance please?
Thanks,
Emi
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