If you only select a few rows, Postgre will decide on an index scan – if you select a majority of them, Postgre will decide on a table scan. But what if you read too much for an index scan to be efficient but too little for a sequential scan? The solution to the problem is to use a bitmap scan. This way, a single block is only used once during a scan. Postgre will first scan the index and compile those rows / blocks, which are needed at the end of the scan. Then Postgre will take this list and go to the table to really fetch those rows.
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Similar ideas to Bitmap scans
Order of the columns matter.
The index is useless if the first column doesn't appear in the WHERE clause.
Example 1:
An index on (t, x) will not be used in this query:
The Time Blocking productivity method compels you to plan your day hour by hour, and prevent multitasking by batching similar tasks together.
When you complain every day, eat junk food, and never work out, those things add up too. That’s how we become miserable. You almost never hear about how one single moment destroyed a person’s life. Of course, tragedies happen. But for the majority of us, we simply let lif...
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