Csaba Ringhofer has posted comments on this change. ( http://gerrit.cloudera.org:8080/17980 )
Change subject: IMPALA-10984: Improve TimestampValue to String casting ...................................................................... Patch Set 3: Code-Review+1 (3 comments) lgtm I have some additional ideas on how to optimize common cases of timestamp formatting, but this patch is ok without them, the comments are more like a brain dump. http://gerrit.cloudera.org:8080/#/c/17980/2/be/src/runtime/timestamp-parse-util.cc File be/src/runtime/timestamp-parse-util.cc: http://gerrit.cloudera.org:8080/#/c/17980/2/be/src/runtime/timestamp-parse-util.cc@271 PS2, Line 271: optional: we could optimize the case when day/month/year are all needed by using boost::gregorian's year_month_day() Here is an example: https://www.boost.org/doc/libs/1_61_0/doc/html/date_time/examples.html#date_time.examples.dates_as_strings My guess is that it is not too common to use only a subset of year/month/date, so we could probably always compute year_month_day if we need any date component. http://gerrit.cloudera.org:8080/#/c/17980/2/be/src/runtime/timestamp-parse-util.cc@305 PS2, Line 305: CATOR: { optional: this could be replaced with a division with a precomputed int in DateTimeFormatContext - the current logic should make Format() much slower if we use low fractional precision, e.g. millisecs At least a benchmark could be added to see how bad it is. A similar thing could be done for AdjustYearToLength() to avoid calling std::pow per row. http://gerrit.cloudera.org:8080/#/c/17980/2/be/src/runtime/timestamp-parse-util.cc@351 PS2, Line 351: DCHECK(!d.is_special()); > Done. After changing AppendToBuffer() now we can't this dcheck, even if we want to write too many characters. My idea is to copy only a limited amount, but increase the pos with the original length to hit the dcheck is something goes wrong. -- To view, visit http://gerrit.cloudera.org:8080/17980 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I4fcb4545d9c9a3fdb38c4db58bb4b1321a429d61 Gerrit-Change-Number: 17980 Gerrit-PatchSet: 3 Gerrit-Owner: Riza Suminto <riza.sumi...@cloudera.com> Gerrit-Reviewer: Bikramjeet Vig <bikramjeet....@cloudera.com> Gerrit-Reviewer: Csaba Ringhofer <csringho...@cloudera.com> Gerrit-Reviewer: Impala Public Jenkins <impala-public-jenk...@cloudera.com> Gerrit-Reviewer: Kurt Deschler <kdesc...@cloudera.com> Gerrit-Reviewer: Riza Suminto <riza.sumi...@cloudera.com> Gerrit-Comment-Date: Fri, 29 Oct 2021 07:11:00 +0000 Gerrit-HasComments: Yes
