Re: [HACKERS] Parallel Seq Scan

Hi David and others! David Fetter writes: > On Tue, Jan 27, 2015 at 08:02:37AM +0100, Daniel Bausch wrote: >> >> Tom Lane writes: >> >> >> Wait for first IO, issue second IO request >> >> Compute >> >> Already have second IO req

Re: [HACKERS] Parallel Seq Scan

ng HDDs can only gain up to ~20% by NCQ, SATA SSDs can easily gain up to 700%. +1 for using effective_io_concurrency to tune for this, since prefetching random addresses is effectively a type of parallel I/O. Regards, Daniel -- MSc. Daniel Bausch Research Assistant (Computer Science) Technische Universität Darmstadt http://www.dvs.tu-darmstadt.de/staff/dbausch -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers

Re: [HACKERS] Parallel Seq Scan

about how to make it work for real. Sorry for dropping in so late... I have done all this two years ago. For TPC-H Q8, Q9, Q17, Q20, and Q21 I see a speedup of ~100% when using IndexScan prefetching + Nested-Loops Look-Ahead (the outer loop!). (On SSD with 32 Pages Prefetch/Look-Ahead + Cold Page C

Re: [HACKERS] State of the on-disk bitmap index

coding helps against the cardinality problems, I will also draw comparisons with different cardinalities. Yours sincerely, Daniel -- Daniel Bausch Wissenschaftlicher Mitarbeiter Technische Universität Darmstadt Fachbereich Informatik Fachgebiet Datenbanken und Verteilte Systeme Hochschulstraße

Re: [HACKERS] State of the on-disk bitmap index

PC-H queries. I will compare B+-tree, bitmap, and encoded bitmap indexes. > So you'd have to run some performance tests against a draft > implementation to get people convinced that it is worth the > effort. Supporting index-only scans Would probably give > you an edge. Yes I will, beca

Re: [HACKERS] State of the on-disk bitmap index

Am 20.08.2012 11:44, schrieb Daniel Bausch: > Actually, I was not involved in writing that paper. I want to use that > idea to show something different. I know of a follow up work by Golam > Rabilul Alam et al. that uses the query history and data mining on that > to optimize for the

Re: [HACKERS] State of the on-disk bitmap index

Am 20.08.2012 09:40, schrieb Albe Laurenz: > Daniel Bausch wrote: >> Hello Jonah, Simon, and the hackers, >> >> I am going to implement a simple kind of "encoded bitmap indexes" > (EBI). >> That is an index type where the bitmap columns may not only contain

[HACKERS] State of the on-disk bitmap index

and therefore will need some assistance most probably. Regards, Daniel -- Daniel Bausch Wissenschaftlicher Mitarbeiter Technische Universität Darmstadt Fachbereich Informatik Fachgebiet Datenbanken und Verteilte Systeme Hochschulstraße 10 64289 Darmstadt Germany Tel.: +49 6151 16 6706 Fax: +49 61