On Oracle
Wednesday, January 7, 2015
open_cursors, session_cached_cursors: cursordump
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1. Parse Oracle (11.2.0.3.0) document wrote: OPEN_CURSORS specifies the maximum number of open cursors (handles to private SQL areas) a...
Monday, December 22, 2014
Local prefixed vs. nonprefixed indexes: Column Null Values
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According to Oracle Doc, Oracle does not index table rows in which all key columns are null except in the case of bitmap indexes ( Database ...
Monday, November 10, 2014
reverse key index: the remedy is worse than the symptoms
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In general, reverse key index mitigates data block contention (buffer busy waits) when inserting monotonically increasing key into right-mos...
Thursday, November 6, 2014
Low High Water Mark, High High Water Mark, and Parallel Query
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Recently we saw a 4 hours running parallel SELECT: select /*+ parallel(t,2) parallel_index(t,2) dbms_stats cursor_sharing_exact use_w...
Friday, May 23, 2014
Oracle 11g AUTO_SAMPLE_SIZE performance on Small Tables
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Oracle 11g enhanced DBMS_STATS.AUTO_SAMPLE_SIZE by a new algorithm in calculating NDV (see Blog: Improvement of AUTO sampling statistics ga...
Thursday, May 8, 2014
java stored procedure calls and latch: row cache objects, and performance
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In the last Blog, we demonstrated java stored procedure calls and latch: row cache objects. Is "latch: row cache objects" a real...
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