R
Rob Fitzpatrick
Guest
Hi Tom, One possibility is that your temp-tables have grown sufficiently large that they are no longer entirely memory-resident so you are seeing a performance decrease due to disk I/O to your client's DBI file. Check the size of your DBI file during the query; if not on Windows you can see it with lsof -p or similar, or start the client with -t to make the temp files visible. If it grows then you're doing disk writes, so your temp-table buffers are too small for your data. Do you specify values for the -tmpbsize and -Bt client startup parameters or use the defaults? If the latter you have about 1 MB of temp-table buffers (4 KB * 255) which may well be insufficient for 55K records and is definitely insufficient for one million. Try bumping up these parameters to give you more buffer space than your max DBI size and see if performance changes. HTH. Rob
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