PostgreSQL

Postgres vs. Oracle access paths VIII – Index Scan and Filter

By Franck Pachot . In the previous post we have seen a nice optimization to lower the consequences of bad correlation between the index and the table physical order: a bitmap, which may include false positives(…)

Postgres vs. Oracle access paths VI – Index Scan

By Franck Pachot . In the previous post my queries were still reading the indexed column only, from a table which had no modifications since the last vacuum, and then didn't need to read table pages:(…)

Postgres vs. Oracle access paths V – FIRST ROWS and MIN/MAX

By Franck Pachot . We have seen how an index can help to avoid a sorting operation in the previous post. This avoids a blocking operation: the startup cost is minimal and the first rows can(…)

Postgres vs. Oracle access paths IV – Order By and Index

By Franck Pachot . I realize that I'm talking about indexes in Oracle and Postgres, and didn't mention yet the best website you can find about indexes, with concepts and examples for all RDBMS: http://use-the-index-luke.com. You(…)

Developer GUI tools for PostgreSQL

There was a recent thread on the PostgreSQL general mailing list asking for GUI tools for PostgreSQL. This is question we get asked often at customers so I though it might be good idea to summarize(…)

A wonderful PostgreSQL feature: default privileges

Imagine this scenario (which is not so uncommon): You have a lot of objects in a user schema and you want to grant another user access to that tables. You can easily do this by granting select(…)

Postgres vs. Oracle access paths III – Partial Index

By Franck Pachot . In the previous post I said that an Index Only Access needs to find all rows in the index. Here is a case where, with similar data, Postgres can find all rows(…)

Postgres vs. Oracle access paths II – Index Only Scan

By Franck Pachot . In the previous post I've explained a sequential scan by accident: my query needed only one column which was indexed, and I expected to read the index rather than the table. And(…)

Postgres vs. Oracle access paths I – Seq Scan

By Franck Pachot . Here is the first test I've done for my Postgres vs. Oracle access paths series and the first query did a sequential scan. It illustrates the first constant you find in the(…)

Postgres unique constraint

By Franck Pachot . I'll start a series on Postgres vs. Oracle access paths because I know Oracle and I learn Postgres. While preparing it, I came upon some surprises because I'm so used to Oracle(…)