Thanks once again Mr. Heikki for your help. Got your point! Thanks :)
-Vaibhav (*_*) On Thu, Nov 18, 2010 at 7:10 PM, Heikki Linnakangas < heikki.linnakan...@enterprisedb.com> wrote: > On 18.11.2010 15:19, Vaibhav Kaushal wrote: > >> I have a small problem: Suppose that I have a table in PostgreSQL which >> has >> a integer field as its Primary key and I have used the Hash indexing >> method >> for creating the index for the field on the table. Now I want to know the >> following details about the index (assuming the machine running PostgreSQL >> is a Linux box with DB installed at /var/lib/pgsql/data): >> >> * Which file would contain the index table data? (OR how to find them? >> Will >> I find them in the CATALOG tables?) >> > > SELECT relfilenode FROM pg_class WHERE relname='index name'. The index data > is stored in a file with that name. Something like > /var/lib/pgsql/data/base/11910/<relfilenode from that query> > > > * Is there some documentation available about the source apart from that >> on >> the website and the the one which gets compiled with the source? >> (specially >> about the conversions and the steps of conversion of the data from they >> raw >> disc reads to the structured layout in the memory just before the executor >> is started) >> > > The source and the README files in the source tree are your best help. And > the comments in the header files are very helpful too. > > > * Which file in the source tree is responsible for the scan of the index? >> (The main file in case there are two of them for the btree and hash >> indexes >> separately) >> > > src/backend/access/nbtree/nbtree.c, btgettuple function > and > src/backend/access/hash/hash.c, hashgettuple function > > src/backend/access/index/indexam.c is the common entry point for all index > types. > > > * Which data structures are the most important ones in index scanning? (I >> will search them myself but please someone tell me the structures; there >> are >> just too many of them :( ) >> > > Depends on what you're interested in. IndexScanDesc is common between all > index scans, Understanding the page structure might also be helpful, see > src/include/storage/bufpage.h. > > > * Are the pages of the DB file layout of the index table in someway >> different than what is discussed at >> http://www.postgresql.org/docs/9.0/interactive/storage-file-layout.html ? >> If >> yes then what are the differences? >> > > No, that applies to indexes too. > > > And I must say that while browsing the source, I was so pleased to read >> the >> comments (they really helped a lot). Thanks to the PostgreSQL coding >> conventions and of course the contributors. I am a bit clear about the >> working of the executor (thanks to ECLIPSE for support of ctags and a nice >> UI) but I am still much in a mess. >> >> Thanks in advance for the answer ;) >> > > Good luck! > > -- > Heikki Linnakangas > EnterpriseDB http://www.enterprisedb.com >
