105 lines
2.3 KiB
SQL
105 lines
2.3 KiB
SQL
--------------------------------------------------------------
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-- Practical SQL: A Beginner's Guide to Storytelling with Data
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-- by Anthony DeBarros
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-- Chapter 19 Code Examples
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--------------------------------------------------------------
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-- VACUUM
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-- Listing 19-1: Creating a table to test vacuuming
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CREATE TABLE vacuum_test (
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integer_column integer
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);
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-- Listing 19-2: Determining the size of vacuum_test
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SELECT pg_size_pretty(
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pg_total_relation_size('vacuum_test')
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);
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-- optional: Determine database size
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SELECT pg_size_pretty(
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pg_database_size('analysis')
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);
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-- Listing 19-3: Inserting 500,000 rows into vacuum_test
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INSERT INTO vacuum_test
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SELECT * FROM generate_series(1,500000);
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-- Test its size again
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SELECT pg_size_pretty(
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pg_table_size('vacuum_test')
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);
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-- Listing 19-4: Updating all rows in vacuum_test
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UPDATE vacuum_test
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SET integer_column = integer_column + 1;
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-- Test its size again (35 MB)
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SELECT pg_size_pretty(
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pg_table_size('vacuum_test')
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);
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-- Listing 19-5: Viewing autovacuum statistics for vacuum_test
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SELECT relname,
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last_vacuum,
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last_autovacuum,
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vacuum_count,
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autovacuum_count
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FROM pg_stat_all_tables
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WHERE relname = 'vacuum_test';
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-- To see all columns available
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SELECT *
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FROM pg_stat_all_tables
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WHERE relname = 'vacuum_test';
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-- Listing 19-6: Running VACUUM manually
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VACUUM vacuum_test;
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VACUUM; -- vacuums the whole database
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VACUUM VERBOSE; -- provides messages
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-- Listing 19-7: Using VACUUM FULL to reclaim disk space
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VACUUM FULL vacuum_test;
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-- Test its size again
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SELECT pg_size_pretty(
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pg_table_size('vacuum_test')
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);
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-- SETTINGS
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-- Listing 19-8: Showing the location of postgresql.conf
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SHOW config_file;
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-- Listing 19-10: Show the location of the data directory
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SHOW data_directory;
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-- reload settings
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-- Mac and Linux: pg_ctl reload -D '/path/to/data/directory/'
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-- Windows: pg_ctl reload -D "C:\path\to\data\directory\"
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-- BACKUP AND RESTORE
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-- Listing 19-11: Backing up the analysis database with pg_dump
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pg_dump -d analysis -U [user_name] -Fc > analysis_backup.sql
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-- Back up just a table
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pg_dump -t 'train_rides' -d analysis -U [user_name] -Fc > train_backup.sql
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-- Listing 19-12: Restoring the analysis database with pg_restore
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pg_restore -C -d postgres -U postgres analysis_backup_custom.sql
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