Questions tagged [bitmap-index]
20 questions
5
votes
3 answers
Loop vectorization - counting matches of 7-byte records with masking
I have a fairly simple loop:
auto indexRecord = getRowPointer(0);
bool equals;
// recordCount is about 6 000 000
for (int i = 0; i < recordCount; ++i) {
equals = BitString::equals(SelectMask, indexRecord, maxBytesValue);
rowsFound +=…
Lukáš Moravec
- 189
- 2
- 8
5
votes
2 answers
How to create bitmap index in PostgreSQL? (Does it even have bitmap index ?)
I have been "googling" at least for an hour, but I was unable to find how to create a bitmap index in PostgreSQL, so my question is very simple: how to write this command (from Oracle) in PostgreSQL:
CREATE BITMAP INDEX name ON table (column);
Baker
- 425
- 1
- 7
- 20
5
votes
2 answers
Bitmapped indexes not enabled in Oracle XE
I am using Oracle 10g XE (express edition). If I try to create a bitmap index, I get an error
ORA-00439 feature not enabled: Bit mapped Indexes
How do I solve this problem and create a bitmap index?
user1391118
- 265
- 2
- 4
- 12
2
votes
1 answer
INSERT Performance - Bitmap vs B-Tree
If we put the select performance aside, which one is faster when it comes to insert. I couldn't find any thorough explanation for this. Can someone please explain? This question just labels bitmaps as inefficient but I want to know why.
Thanks,
Emre Türkiş
- 992
- 9
- 23
2
votes
4 answers
Can we create Bitmap Index on a table column in Oracle 11 which reloads daily using a Job
We have table which stores information about clients which gets loaded using a scheduled job on daily basis from Data warehouse. There are more than 1 million records in that table.
I wanted to define BitMap Index on Country column as there would be…
user3284850
- 21
- 5
2
votes
1 answer
Bitmap index search results array: finding the indices of nonzero elements in constant time?
As far as I understand it, a bitmap index search will return an array of 0s and 1s, like below:
[0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0]
Each index in the array is mapped to some record in the database in some other array, so to get results you…
user2108462
- 855
- 7
- 23
2
votes
1 answer
Is the compressed size of all bitmap indices for a particular column at most proportional to the size of your table?
I was reading Daniel Lemire's post The Mythical Bitmap Index (http://lemire.me/blog/archives/2008/08/20/the-mythical-bitmap-index/) and in the post he says
the compressed size of a bitmap index is at most proportional to the size of your table!…
user2108462
- 855
- 7
- 23
1
vote
2 answers
The oracle server hang when inserting rows into a dimension table
There are two tables. The first is a fact table, about 0.1 billion rows. The other is a dimension table with only about 100 rows. I have made a bitmap-join index on the fact table to
optimize the query.
However, when I insert a few rows into the…
sgzhan
- 51
- 8
1
vote
1 answer
Is it possible to use bitmap index with more than two possible values?
It clear how bitmap indexes works with two possible values (gender: male and female). But how is it possible to use with 3 or more values?
Can anyone explain how it works in postgresql?
Lapkovsky Kirill
- 59
- 1
- 7
1
vote
1 answer
Oracle Function based Bitmap Index
I'm using Oracle 11g and I have three tables, viz, TABLE_1, TABLE_2, TABLE_3. In a select statement I need to execute the following query:
SELECT
-- // ommitted
FROM
TABLE_1,
TABLE_2,
TABLE_3
WHERE
-- // ommitted
AND…
Tapas Bose
- 28,796
- 74
- 215
- 331
1
vote
2 answers
Can oracle merge bitmap indexes during fast full scan?
I have a large fact table with 300M rows and 50 columns in it. There are multiple reports over this table and each report uses only couple out of 50 columns from the table.
Each column in the fact table is indexed with BITMAP INDEX. The idea is to…
Volodymyr Frolov
- 1,256
- 5
- 16
- 25
0
votes
1 answer
Oracle not using my bitmap index if I query for all columns
I created a bitmap index for my table on column_x. Keep in mind that column x has low cardinality, only 20 unique values out of 100,000 rows of data.
Then I query
SELECT * FROM table_1
WHERE column_x = 'xyz'
But instead of doing an index scan, it…
UrDailyCS
- 17
- 6
0
votes
1 answer
Why my bitmap index doesnt speed up my query
So i define bitmap index for column_a. then i query
Select column_a, column_b
from table_name
where column_a = 'values';
But after i check the Explain plan, my query still do a table access full scan. but if i only do
Select column_a
from…
UrDailyCS
- 17
- 6
0
votes
1 answer
Clickhouse- Search array of strings using inverted indexes
I have table with column type Array(String)
CREATE TABLE db.logs
( `timestamp` DateTime CODEC(Delta(4),
ZSTD(1)),
`message` String,
`source_type` LowCardinality(String),
`labels_key` Array(String),
`labels_value` Array(String),
…
Majid Chaudhary
- 41
- 6
0
votes
1 answer
Text / Document search in clickhouse
I have a table with approx. 10 billion distinct rows, which has a String column with log messages.
The problem is to search this column with 'like' operator to match part of text. Once result is received, then select and display the entire row.
What…
Majid Chaudhary
- 41
- 6