I have a script that runs several times in the evening, and on each
run it adds several thousand entries to a table.
On the first run, it adds the entries rather slowly. But then on all
subsequent runs (usually about a minute or two later), the many
inserts go a lot faster. This is true regardless of how many entries
are added by each run -- whether the first and second run both add
50,000 or the first and second run both add 10,000, the first run
goes slowly and the second one goes fast. But by the following
evening, the first run is back to going slowly again.
It's as if in the minute or two following the first run of the
script, MySQL catches its breath and realizes, hey, that table is
getting a lot of entries added to it, so it waves some magic dust so
that the next time I add a lot of entries, it goes a lot
faster. (Hope I'm not losing anybody with the technical terminology
here.) Then by the next evening the optimization parameter has
exp^W^W^W^W the fairy dust has worn off.
Is this a familiar phenomenon to anyone? Know why it's
happening? And especially, is there any way I can tell MySQL to
optimize that table before the first script run, so that the first
run goes fast as well?
In general, does anybody have familiarity with the strategies for
speeding up the process of inserting a lot of rows at a time, and
knows which ones really do work and which ones don't? This page:
http://dev.mysql.com/doc/refman/5.0/en/insert-speed.html
says that in the case of a single client doing lots of inserts, these
would apply:
- using insert statements with multiple values lists
- change the "bulk_insert_buffer_size" variable
- writing the data to be inserted into a temporary file, and then
using the LOAD DATA INFILE syntax
-Bennett
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