Configure merge_block_size in sphinx search engine

Question

I am powering a web search using Sphinx, and am getting the following error message while building the indexes:

WARNING: sort_hits: merge_block_size=76 kb too low, increasing mem_limit may improve performance

The problem is I can't find any documentation on where this setting is configured. I'm somewhat versed on Sphinx setup, so I just need to know where the setting is configured.

Answer 1

This is probably happening because you're trying to index too many items at once. Make sure you're using ranged queries. If you're already using ranged queries, increasing the mem_limit, as it suggests, may help. The merge_block_size is based on mem_limit and the number of documents.

If you're curious as to how it generates that number, check out the source. It's freely available.