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On DBD::SQLite of SQLite3
If I am going to query a SELECT only once.
Should I CREATE a INDEX first and then query the SELECT
or
just query the SELECT without an INDEX,
which is faster ?
If need to be specified, the col. to be index on is a INTEGER of undef or 1, just these 2 possibilities.
Building an index takes longer than just doing a table scan. So, if your single query — which you’re only running once — is just a table scan, adding an index will be slower.
However, if your single query is not just a table scan, adding the index may be faster. For example, without an index, the database may perform a join as many table scans, once for each joined row. Then the index would probably be faster.
I’d say to benchmark it, but that sounds silly for a one-off query that you’re only ever going to run once.