RE: bitmap index and distinct values
From: Iggy Fernandez <iggy_fernandez_at_hotmail.com>
Date: Sun, 26 Apr 2015 19:44:34 -0700
Message-ID: <BLU179-W9594AC877A128FB314D4DEBE90_at_phx.gbl>
In other words (if I correctly understand what Jonathan is saying), a bitmap index is a B-tree structure (the same structure used by a normal index). In a normal index, the entries are (<key>, <ROWID>) pairs but, in a bitmap index, the entries are (<distinct value>, <start ROWID>, <compressed bitmap chunk>).
Date: Sun, 26 Apr 2015 19:44:34 -0700
Message-ID: <BLU179-W9594AC877A128FB314D4DEBE90_at_phx.gbl>
In other words (if I correctly understand what Jonathan is saying), a bitmap index is a B-tree structure (the same structure used by a normal index). In a normal index, the entries are (<key>, <ROWID>) pairs but, in a bitmap index, the entries are (<distinct value>, <start ROWID>, <compressed bitmap chunk>).
Iggy
-- http://www.freelists.org/webpage/oracle-lReceived on Mon Apr 27 2015 - 04:44:34 CEST