|
|
|
|
@ -250,12 +250,17 @@ Indexes |
|
|
|
|
order. Another method would be to sort heap ctids matching the index |
|
|
|
|
before accessing the heap rows. |
|
|
|
|
|
|
|
|
|
* Use bitmaps to combine existing indexes [performance] |
|
|
|
|
* Allow the creation of bitmap indexes which can be quickly combined |
|
|
|
|
with other bitmap indexes |
|
|
|
|
|
|
|
|
|
Bitmap indexes allow single indexed columns to be combined to |
|
|
|
|
dynamically create a composite index to match a specific query. Each |
|
|
|
|
index is a bitmap, and the bitmaps are AND'ed or OR'ed to be combined. |
|
|
|
|
Bitmap indexes index single columns and can be combined with other bitmap |
|
|
|
|
indexes to dynamically create a composite index to match a specific query. |
|
|
|
|
Each index is a bitmap, and the bitmaps are bitwise AND'ed or OR'ed to be |
|
|
|
|
combined. |
|
|
|
|
|
|
|
|
|
* Allow non-bitmap indexes to be combined |
|
|
|
|
|
|
|
|
|
Do loUse bitmaps to combine non-bitmap indexes |
|
|
|
|
* Allow use of indexes to search for NULLs |
|
|
|
|
|
|
|
|
|
One solution is to create a partial index on an IS NULL expression. |
|
|
|
|
|