explain.depesz.com

PostgreSQL's explain analyze made readable

Result: QecV : Optimization for: plan #SyvH

Settings

Optimization path:

# exclusive inclusive rows x rows loops node
1. 0.006 831.383 ↑ 1.0 1 1

Nested Loop (cost=284,373.72..284,373.75 rows=1 width=24) (actual time=831.381..831.383 rows=1 loops=1)

2. 0.010 0.010 ↑ 1.0 1 1

Function Scan on unnest un (cost=0.00..0.01 rows=1 width=8) (actual time=0.009..0.010 rows=1 loops=1)

3. 0.002 831.367 ↑ 1.0 1 1

Limit (cost=284,373.72..284,373.72 rows=1 width=24) (actual time=831.366..831.367 rows=1 loops=1)

4. 105.138 831.365 ↑ 436,876.0 1 1

Sort (cost=284,373.72..285,465.91 rows=436,876 width=24) (actual time=831.365..831.365 rows=1 loops=1)

  • Sort Key: raw.timestamp_utc DESC
  • Sort Method: top-N heapsort Memory: 25kB
5. 94.674 726.227 ↓ 1.1 485,302 1

Custom Scan (ChunkAppend) on raw (cost=0.56..282,189.34 rows=436,876 width=24) (actual time=0.032..726.227 rows=485,302 loops=1)

6. 631.553 631.553 ↓ 1.1 485,302 1

Index Scan using _hyper_1_6_chunk_timeseries_idx_raw_test on _hyper_1_6_chunk (cost=0.56..282,189.34 rows=436,876 width=24) (actual time=0.032..631.553 rows=485,302 loops=1)

  • Index Cond: (tag_id = un.tag_id)