On 24/08/2020 19.43, Roberto Cornacchia wrote:
Hi, I was looking at pcre.c for some inspiration and found something suspicious.
At the end of both pcre_likeselect() and re_likeselect():
if (bn && !msg) { BATsetcount(bn, BATcount(bn)); /* set some properties */ bn->tsorted = true; bn->trevsorted = bn->batCount <= 1; bn->tkey = true; bn->tseqbase = bn->batCount == 0 ? 0 : bn->batCount == 1 ? * (oid *) Tloc(bn, 0) : oid_nil; }
Which I read as: if everything went well, then the result is sorted and key. But I miss why it should be sorted and key.
They are sorted because of the way the BAT is created. Remember, a select returns a "candidate list", an ordered list of matching OIDs. The list is created by going through the OIDs of the to-be-selected bat and adding the OID to the result when there is a match.
Roberto
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