Re: [HACKERS] PG process architecture
EnterpriseDB is a clone AND a fork. :-) We work hard to free customers from Oracle vendor lock-in AND stay up with the latest releases and patches of Postgres AND don't break any Postgres native and/or ANSI functionality. --Denis Lussier Founder CTO www.EnterpriseDB.com On 1/11/06, Joshua D. Drake [EMAIL PROTECTED] wrote: EnterpriseDB is not a clone, it is a fork. That said, it is very coolthat theyhave created an Oracle look-a-like for much less but if you want PostgreSQL that isn't EnterpriseDB.
[HACKERS] PG process architecture
Hi listers, I am experienced Oracle DBA und now I was given a task to evaluate Postgresql. May first goal is to compare the architecture of Oracle and Postgres. After reading the fine manuals and several mailing lists, I have found that the following parameters are analogous in PG vs Oracle shared_buffers - db_cache_size wal_buffers - log_buffer shared_buffers and wal_buffers are residing in shared memory segments. My questions is: Where PG is storing data dictionary information (coming form system pg_* tables) while parsing the queries ? I suppose each each background process is parsing (and eventually caching) the parsed SQL statements in his own memory (within each backend process), aka there is no SHARED_POOL as in Oracle. That would mean that backand processes don't have a common place to check whether sa same SQL query (with the same planner environment) is already parsed (and ready for execution). That would mean that each backend process could reuse only his own parsed statements (provided that bind variables are used) Is there any parameter (apart from geqo_pool_size, I suppose) that limits the size of this private pool memory in each backend process? Consider the following scenario. If I have a system with 50 or 100 connection (and the corresponding 100 backend processes), and one session creates an index on a given table, how do the other 99 processes notice that they can use (or at least estimate the appropriatness of the usage of) the new index ? How PG ist doing this ? I would be very grateful if someone can sched some light /links, previous postings, comments/ on this topic. Regards, Milen -- Telefonieren Sie schon oder sparen Sie noch? NEU: GMX Phone_Flat http://www.gmx.net/de/go/telefonie ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
Re: [HACKERS] PG process architecture
Milen Kulev [EMAIL PROTECTED] writes: My questions is: Where PG is storing data dictionary information (coming form system pg_* tables) while parsing the queries ? There's a limited-size catalog cache in each backend process, which might be the closest analogy to this. Offhand I think it's fixed at 5000 rows --- there's no user-visible knob to control it, anyway. I suppose each each background process is parsing (and eventually caching) the parsed SQL statements in his own memory (within each backend process), There is no such cache. If you tell us to PREPARE something, we save the plan, otherwise not. If I have a system with 50 or 100 connection (and the corresponding 100 backend processes), and one session creates an index on a given table, how do the other 99 processes notice that they can use (or at least estimate the appropriatness of the usage of) the new index ? There's a cache-invalidation signaling mechanism for the catcache, which is what drives this sort of thing. regards, tom lane ---(end of broadcast)--- TIP 4: Have you searched our list archives? http://archives.postgresql.org
Re: [HACKERS] PG process architecture
Hi Harris, from oracle DBA point of view Enterprise DB is VERY cool. My boss will be very happy to hear that there a way to get (paid) support for a PG DB. But at the end I want to undestand how PG (and its clone Enterprise DB ) is working ;) . Hopefully I don't need to read the whole source of PG (several times) to understand a little bit deeper the internal mechanics of PG. Regards. Milen. --- Ursprüngliche Nachricht --- Von: Jonah H. Harris [EMAIL PROTECTED] An: Milen Kulev [EMAIL PROTECTED] Betreff: Re: [HACKERS] PG process architecture Datum: Wed, 11 Jan 2006 09:44:31 -0500 As an Oracle DBA, you may want to take a look at EnterpriseDB ( http://www.enterprisedb.com/) On 1/11/06, Milen Kulev [EMAIL PROTECTED] wrote: Hi listers, I am experienced Oracle DBA und now I was given a task to evaluate Postgresql. May first goal is to compare the architecture of Oracle and Postgres. After reading the fine manuals and several mailing lists, I have found that the following parameters are analogous in PG vs Oracle shared_buffers - db_cache_size wal_buffers - log_buffer shared_buffers and wal_buffers are residing in shared memory segments. My questions is: Where PG is storing data dictionary information (coming form system pg_* tables) while parsing the queries ? I suppose each each background process is parsing (and eventually caching) the parsed SQL statements in his own memory (within each backend process), aka there is no SHARED_POOL as in Oracle. That would mean that backand processes don't have a common place to check whether sa same SQL query (with the same planner environment) is already parsed (and ready for execution). That would mean that each backend process could reuse only his own parsed statements (provided that bind variables are used) Is there any parameter (apart from geqo_pool_size, I suppose) that limits the size of this private pool memory in each backend process? Consider the following scenario. If I have a system with 50 or 100 connection (and the corresponding 100 backend processes), and one session creates an index on a given table, how do the other 99 processes notice that they can use (or at least estimate the appropriatness of the usage of) the new index ? How PG ist doing this ? I would be very grateful if someone can sched some light /links, previous postings, comments/ on this topic. Regards, Milen -- Telefonieren Sie schon oder sparen Sie noch? NEU: GMX Phone_Flat http://www.gmx.net/de/go/telefonie ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings -- 10 GB Mailbox, 100 FreeSMS/Monat http://www.gmx.net/de/go/topmail +++ GMX - die erste Adresse für Mail, Message, More +++ ---(end of broadcast)--- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
Re: [HACKERS] PG process architecture
Milen Kulev wrote: Hi Harris, from oracle DBA point of view Enterprise DB is VERY cool. My boss will be very happy to hear that there a way to get (paid) support for a PG DB. There several highly qualified support vendors for PostgreSQL: SRA America Pervasive and ourselves, the only dedicated PostgreSQL support vendor; Command Prompt. But at the end I want to undestand how PG (and its clone Enterprise DB ) is working ;) . EnterpriseDB is not a clone, it is a fork. That said, it is very cool that they have created an Oracle look-a-like for much less but if you want PostgreSQL that isn't EnterpriseDB. Sincerely, Joshua D. Drake -- The PostgreSQL Company - Command Prompt, Inc. 1.503.667.4564 PostgreSQL Replication, Consulting, Custom Development, 24x7 support Managed Services, Shared and Dedicated Hosting Co-Authors: PLphp, PLperl - http://www.commandprompt.com/ ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
