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?


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