Some days ago i came across with a pl/sql code where they used (for some reason) an Oracle hint called SYS_DL_CURSOR. I got it when i…
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Category: performance
APPEND_VALUES and SYS_DL_CURSOR Hints with HCC
The APPEND_VALUES hint was introduced in 11.2 to allow direct path inserts with variables using the VALUES clause. i.e. INSERT INTO XYZ (COL1, COL2) VALUES…
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PostgreSQL “bind variable peeking”
custom vs. generic plans With my Oracle database background, I know how important it is to balance the pros and cons of using bind variables…
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Postgresql PREPARE — prepare a statement for execution
Synopsis PREPARE name [ ( data_type [, …] ) ] AS statement Description PREPARE creates a prepared statement. A prepared statement is a server-side object that…
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Adaptive Cursor Sharing in Oracle Database 11g Release 1
DBAs are always encouraging developers to use bind variables, but when bind variables are used against columns containing skewed data they sometimes lead to less…
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How to Swap SQL_Profiles?
The central idea behind “swapping” SQL profiles is simple. You define a SQL profile that specifies the SQL statement that you want to tune, and an…
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SQL Profiles in the Data Dictionary
In the paper SQL Profiles (page 22) I described the data dictionary tables where the hints belonging to SQL profiles are stored. For example, with the following…
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Useful Gather Statistics Commands In Oracle
This article contains all the useful gather statistics related commands. 1. Gather dictionary stats: — It gathers statistics for dictionary schemas ‘SYS’, ‘SYSTEM’ and other…
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CURSOR_SHARING=SIMILAR AND FORCE – SOME EXAMPLES
The CURSOR_SHARING parameter basically influences the extent to which SQL statements (or cursors) can be shared. The possible values are EXACT which is the default…
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12c: Optimizer_Dynamic_Sampling = 11
With default sampling level of 2 (from 10g onwards) , dynamic sampling is performed only for the objects for which statistics do not exist. If…
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