I think you are approaching the problem from the wrong end.

Trying to determine the similarity of queries by comparing the SQL is problematic. For example, all these queries are textually similar, but produce quite different results sets: 

select thing from tableA;
select thing from tableA limit 1000 offset 1000;
select count( thing ) from tableA;
select thing from tableB;

[download]

Conversely, it not hard to dream up two or more radically different queries that produce identical results sets. Throw in a few joins and sub-selects and you would likely never determine their similarity.

If your intention is to try and cache the results from long running queries and re-use them, I think you will have an inordinately big task.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

In reply to Re: Trimming hash based on element uniqueness by BrowserUk
in thread Trimming hash based on element uniqueness by mhearse

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