In this video, learn about bitmap indexes.
- [Instructor] Let's take a look … at a special kind of index that is well-suited … for low cardinality columns. … That is the Bitmap Index. … Bitmap Indexes store a series of bits … for indexed values. … The number of bits used is the same … as the number of distinct values in a column. … For example, a column that has either a yes or no value … would require two bits. … One corresponding to the yes, … and one corresponding to the no. … Now, we aren't restricted to bullion, … or yes no columns. … We could have three or more values. … For example, if we have a pay type, … which can have three possible values, … then we would use three bits to represent each value. … One of the advantages of Bitmap Indexes … is that we can perform bullion operations quickly. … For example, performing an and operation on two bitmaps … is a fast operation. … So we could use it to find all union members … who have an hourly pay type in our example. … Bitmap's are used with low cardinality columns, … especially when we want to filter on those columns …
Author
Released
4/1/2019- How SQL executes queries
- Working with PostgreSQL tools for tuning
- Bitmap and hash indexes
- Using different types of indexes to improve performance
- Challenges with joining tables
- When to use partitioning to improve performance
- Collecting statistics about data in tables
Skill Level Advanced
Duration
Views
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Introduction
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1. How SQL Executes a Query
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Scanning tables and indexes3m 12s
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Joining tables2m 24s
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Partitioning data2m 23s
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2. PostgreSQL Tools for Tuning
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Installing PostgreSQL2m 41s
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Overview of pgAdmin3m 21s
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Explain and analyze3m 37s
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Indexes3m 7s
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3. Types of Indexes
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Indexing3m 1s
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B-tree indexes2m 2s
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B-tree index example plan2m 18s
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Bitmap indexes1m 46s
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Bitmap index example plan2m 39s
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Hash indexes1m 19s
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Hash index example plan1m 32s
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PostgreSQL-specific indexes1m 17s
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4. Tuning Joins
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Nested loops3m 19s
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Nested loop example plan3m 55s
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Hash joins1m 25s
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Hash join example plan1m 57s
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Merge joins2m 17s
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Merge join example3m 16s
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Subqueries vs. joins1m 11s
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5. Partitioning Data
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Partition by range2m 6s
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Partition by list1m 37s
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Partition by list example4m 55s
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Partition by hash2m 12s
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Partition by hash example4m 51s
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6. Materialized Views
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Materialized views1m 41s
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7. Other Optimization Techniques
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Hints to the query optimizer2m 13s
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Parallel query execution2m 3s
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Miscellaneous tips1m 47s
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Conclusion
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Next steps41s
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Video: Bitmap indexes