Re: Cube Index Size
От | Heikki Linnakangas |
---|---|
Тема | Re: Cube Index Size |
Дата | |
Msg-id | 4DE495B1.4060802@enterprisedb.com обсуждение исходный текст |
Ответ на | Cube Index Size (Nick Raj <nickrajjain@gmail.com>) |
Список | pgsql-hackers |
On 30.05.2011 21:51, Nick Raj wrote: > Hi, > > Cube code provided by postgres contrib folder. It uses the NDBOX structure. > On creating index, it's size increase at a high rate. > > On inserting some tuple and creating indexes its behaviour is shown below. > > 1. When there is only one tuple > select pg_size_pretty(pg_relation_ > size('cubtest')); //Table size without index > pg_size_pretty > ---------------- > 8192 bytes > (1 row) > > select pg_size_pretty(pg_total_relation_size('cubtest')); //Table size with > index > pg_size_pretty > ---------------- > 16 kB > (1 row) > > i.e. Index size in nearly 8kB > > 2. When tuples are 20,000 > > Table Size without index - 1.6 MB > Table Size with index - 11 MB > i.e. Index size is nearly 9.4 MB > > 3. When tuples are 5 lakh > > Table Size without index - 40 MB > Table Size with index - 2117 MB > i.e. Index size is nearly 2077 MB ~ 2GB > It is taking nearly 20-25 min for creating index for 5 lakh tuples. > > Can some one tell me why index is becoming so large? > How to compress or reduce its size? Which version of PostgreSQL are you using? I wonder if this could be due to the bug in cube's picksplit algorithm that was fixed a while ago: http://archives.postgresql.org/message-id/AANLkTimC8W6guHpWJeWdjQA6WGoVH-7qG9Ar4pem2N2V@mail.gmail.com If not, please post a self-contained test case to create and populate the table, so that others can easily try to reproduce it. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
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