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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have a large fact table (millions of entries) and several modes for its use. I’m not econfident I am getting optimal use of the indices.<o:p></o:p></p>
<p class="MsoNormal">Is there a technique like with most SQL databases where one can EXPLAIN the query to see what plan is used?
<o:p></o:p></p>
<p class="MsoNormal">The way I read the goals it would happen in an order I expect, but the performance isn’t good.<o:p></o:p></p>
<p class="MsoNormal">I can’t afford to make modes for all possible combinations. The fact table would take weeks to compile and hundreds of gigabytes of RAM (for the C compiler).<o:p></o:p></p>
<p class="MsoNormal">Because of the size of the table I put it in a shared library, but then I have trouble with deep profiling:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">#0 0x00002aad782b33c1 in __strlen_sse2_pminub () from /usr/lib64/libc.so.6<o:p></o:p></p>
<p class="MsoNormal">#1 0x00002aaaaaaf9028 in MR_write_string (fp=fp@entry=0x5ece40, ptr=0x0) at mercury_deep_profiling.c:1631<o:p></o:p></p>
<p class="MsoNormal">#2 0x00002aaaaaaf970a in MR_write_out_module_proc_reps_start (procrep_fp=0x5ece40,
<o:p></o:p></p>
<p class="MsoNormal"> module_layout=0x2aabc2eac6e0 <mercury__sharedVertex__sharedVertex_fact_table_hash_table_3_4825_data+3360>)<o:p></o:p></p>
<p class="MsoNormal"> at mercury_deep_profiling.c:817<o:p></o:p></p>
<p class="MsoNormal">#3 0x00002aab490a68bf in mercury__sharedVertex__write_out_proc_statics () from ./libsharedVertex.so<o:p></o:p></p>
<p class="MsoNormal">#4 0x0000000000410da1 in ?? ()<o:p></o:p></p>
<p class="MsoNormal">#5 0x00002aaaaaafa00e in MR_write_out_profiling_tree () at mercury_deep_profiling.c:479<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks for any suggestions,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Marcus<o:p></o:p></p>
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