Beginning with this release of the InnoDB Plugin, you can use the attributes ROW_FORMAT=COMPRESSED or KEY_BLOCK_SIZE in the CREATE TABLE and ALTER TABLE commands to request InnoDB to compress each page to 1K, 2K, 4K, 8K, or 16K bytes.

— InnoBASE OY

, 3.2. Specifying Compression

A "gotcha" is a feature or function which works as advertised - but not as expected.

— http://sql-info.de/mysql/gotchas.html

behaviour [...] is the diametrical opposite of the default behaviour of most other databases. (Tested: DB2 8.1, Firebird 1.5.1, Oracle 8.1.7 and PostgreSQL 7.4.3 [...])

— http://sql-info.de/mysql/gotchas.html#1_4

it can only insert a single value at a time. This is a major performance limitation, and also suffers concurrency issues. INSERT IGNORE and REPLACE handle multi-valued inserted much more gracefully.

— Robin Johnson

, PostgreSQL Vs. MySQL for INSERT IGNORE + REPLACE - stored procedures, savepoints and beyond

InnoDB tables support checking of foreign key constraints... For other storage engines, MySQL Server parses and silently ignores the FOREIGN KEY and REFERENCES syntax in CREATE TABLE statements.

—MySQL AB

,MySQL 5.1 Reference Manual:: 12.1.9. CREATE TABLE Syntax

MySQL follows the SQL:2003 syntax for stored routines, which is also used by IBMs DB2.

—MySQL AB

,MySQL 5.1 Reference Manual:: 18 Stored Procedures and Functions

MySQL triggers are activated by SQL statements only. They are not activated by changes in tables made by APIs that do not transmit SQL statements to the MySQL Server; in particular, they are not activated by updates made using the NDB API.

—MySQL AB

,MySQL 5.1 Reference Manual:: 19 Triggers

A partial index is an index built over a subset of a table; the subset is defined by a conditional expression (called the predicate of the partial index). The index contains entries for only those table rows that satisfy the predicate. Partial indexes are a specialized feature, but there are several situations in which they are useful.

One major reason for using a partial index is to avoid indexing common values. Since a query searching for a common value (one that accounts for more than a few percent of all the table rows) will not use the index anyway, there is no point in keeping those rows in the index at all. This reduces the size of the index, which will speed up queries that do use the index. It will also speed up many table update operations because the index does not need to be updated in all cases.

—PostgreSQL

,PostgreSQL 8.2.6 Documentation: Chapter 11. Indexes

MySQL is an open-source PRODUCT.

Postgres is an open-source PROJECT.

— Greg Sabino Mullane

,Postgres is not for sale (reprint of original blog post)

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