In a word, no. Unless the query returns a constant value, the run time
will depend on the values of the data and on what machine it's being run
on and the easiest way to determine those things are to actually run the
query.
If what you want is guidance about which queries are going to need
optimization, the cost output from the EXPLAIN command will probably
tell you where to spend your time. The cost output will also tell you
whether you have succeeded in improving the relative performance of a
query without actually having to run it.
Ruven Brooks
On 8/3/2020 9:56 AM, Shaozhong SHI wrote:
Hi,
I tried to use "explain" to look into the query plan. It only gives
me the cost and rows, and does not give an estimate of time to run the
query.
"Explain analyze" gives an estimate of time needed, but for a Big Data
query, one has to wait to get an answer,
Is there a way to get an estimate of time for running a query, without
actually running it.
Looking forward to hearing from you.
Regards,
Shao
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