Create Index field on mapd


Hi, i have 130 million record data on table mapd, and it have 25 fields, when i query it using SELECT * FROM “table” LIMIT 1000 always take much longer time. So, can i create index to field on mapd? if it can to create index, i’ll be thankfully :slight_smile:



Hi @rejanuiss,

Thanks for your interest in MapD.

You can’t create indexes in MapD as we focus on fast scan performance (not saying it won’t ever happen, but its not a current focus area). Unfortunately our way of handling large projection queries (i.e. non-grouped queries) has always needed some optimization. The good news is that with the next release, a change will land that will make these sorts of queries much faster (commit here). Then there is another optimization that will hopefully land in the release after that that should make it even faster.

Note that these optimizations won’t speed up the initial time of loading data from disk, but rather make our in-memory projections more efficient. We have some ideas on selective fetching from disk as well, but likely won’t get to that for a bit.



thanks for reply, so i change my query limit or choose some field that i needed ? which one better?




Try to add some where clauses. Try to be more selective about the things you select.



Try with pseudo column rowid, but dont forget you are querying an analitical rdbms not a transactional one


@rejanuiss were any of these suggestions helpful?


well, suggestions from @todd most helpfully. and i decrease fields into 10 fields :smile: