TimeScale Notes: Difference between revisions
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=== Check Distinct Values === | === Check Distinct Values === | ||
<code> | |||
-- n_distinct (-1 = Unique, 1 = All The Same) | -- n_distinct (-1 = Unique, 1 = All The Same) | ||
SELECT tablename, attname, most_common_vals, most_common_freqs, n_distinct | SELECT tablename, attname, most_common_vals, most_common_freqs, n_distinct | ||
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-- WHERE tablename = '<TableName>'; | -- WHERE tablename = '<TableName>'; | ||
WHERE schemaname = '<SchemaName>'; | WHERE schemaname = '<SchemaName>'; | ||
</code> | |||
=== Compress Table === | === Compress Table === | ||
Revision as of 20:25, 7 April 2025
Compression
Check Distinct Values
-- n_distinct (-1 = Unique, 1 = All The Same)
SELECT tablename, attname, most_common_vals, most_common_freqs, n_distinct
FROM pg_stats
-- WHERE tablename = '<TableName>';
WHERE schemaname = '<SchemaName>';
Compress Table
ALTER TABLE crypto_ticks SET (timescaledb.compress,
timescaledb.compress_segmentby='symbol',
timescaledb.compress_orderby='time DESC');
SELECT compress_chunk(c) from show_chunks('crypto_ticks') c;
Check Compression
SELECT pg_size_pretty(before_compression_total_bytes) as before,
pg_size_pretty(after_compression_total_bytes) as after
FROM hypertable_compression_stats('crypto_ticks');
Compression Policy
SELECT add_compression_policy('crypto_ticks', INTERVAL '8 days');
Links
- HyperCore: Since version 2.18.0
[2] (Old) [3] (New)