Ryan Malloy
13d49c1072
Space-Track USSPACECOM catalog: 29,784 objects from full GP query. Benchmark shows SP-GiST index reaches parity with seqscan at 30k: - Delta: +1.6ms (14k) -> +0.9ms (20k) -> +0.0ms (30k) - Planner voluntarily chooses Index Only Scan at this scale - Zero heap fetches (all data served from index pages) - 75.9% candidate pruning on 2h/10deg query Archive includes TLEs from Space-Track, TLE API, and SatNOGS.
116 lines
4.6 KiB
Plaintext
116 lines
4.6 KiB
Plaintext
pg_orrery v0.7.0 SP-GiST Benchmark — 30k Space-Track Catalog
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Date: 2026-02-17
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Catalog: Space-Track USSPACECOM full catalog (29,784 objects)
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Host: Linux 6.16.5-arch1-1, PostgreSQL 17
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Branch: phase/spgist-orbital-trie
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Catalog Composition:
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LEO (<128 min): 25,641 (86.1%)
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MEO (128-720 min): 1,801 ( 6.0%)
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GEO/HEO (720-1500 min): 2,253 ( 7.6%)
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Super-GEO (>1500 min): 89 ( 0.3%)
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Index Build:
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SP-GiST: 46.7 ms, 4,816 kB
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GiST: 65.8 ms, 5,856 kB
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Table: 4,760 kB
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TIMING RESULTS (best of 3 runs, ms)
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Query Pattern | Seqscan | SP-GiST | Delta
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-----------------------------|---------|---------|-------
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2h window, Eagle ID, 10 deg | 5.19 | 5.22 | +0.03
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6h window, Eagle ID, 10 deg | 5.34 | 6.34 | +1.00
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24h window, Eagle ID, 10 deg | 5.42 | 6.68 | +1.26
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2h window, Eagle ID, 30 deg | 5.54 | 5.64 | +0.10
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2h window, equatorial, 10deg | 5.26 | 5.59 | +0.33
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PRUNING RESULTS
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Query Pattern | Candidates | % Pass | % Pruned
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-----------------------------|------------|--------|---------
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2h window, Eagle ID, 10 deg | 7,188 | 24.1% | 75.9%
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6h window, Eagle ID, 10 deg | 12,373 | 41.5% | 58.5%
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24h window, Eagle ID, 10 deg | 26,971 | 90.6% | 9.4%
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2h window, Eagle ID, 30 deg | 5,232 | 17.6% | 82.4%
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2h window, equatorial, 10deg | 4,670 | 15.7% | 84.3%
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BUFFER I/O COMPARISON (2h Eagle 10deg)
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Method | Pages Read | Heap Fetches | Scan Type
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------------|------------|--------------|------------------
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Seqscan | 595 | n/a | Seq Scan
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SP-GiST | 2,396 | 0 | Index Only Scan
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SP-GiST reads 4.0x more pages than seqscan (2,396 vs 595).
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But uses Index Only Scan with zero heap fetches.
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CONSISTENCY CHECK
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False negatives: 0 (index never misses a seqscan result)
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False positives: 0 (index never returns extra results)
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Seqscan count: 7,188
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SP-GiST count: 7,188
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SCALING TREND (2h Eagle 10deg, best-of-3)
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Catalog Size | Seqscan | SP-GiST | Delta | SP-GiST Pages | Seq Pages
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-------------|---------|---------|--------|---------------|----------
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14,376 | 4.5 ms | 6.1 ms | +1.6ms | 888 | 291
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20,597 | 3.8 ms | 4.7 ms | +0.9ms | (IOOS) | (est)
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29,784 | 5.2 ms | 5.2 ms | +0.0ms | 2,396 | 595
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The delta is converging toward zero. At 30k the SP-GiST index is
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essentially tied with seqscan on the 2h/10deg query. For queries
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with fewer survivors (30deg elevation, equatorial observer), the
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index is within 0.1-0.3ms.
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PLANNER BEHAVIOR
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PostgreSQL's query planner CHOOSES the SP-GiST index by default
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at 30k (without any enable_seqscan=off forcing). The planner's
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cost model prefers the Index Only Scan.
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EXPLAIN output (default settings):
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Index Only Scan using bench_spgist on bench_catalog
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Index Cond: (tle &? ...)
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Heap Fetches: 0
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Buffers: shared hit=2396
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Execution Time: 7.246 ms (with planning)
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NOTES
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1. At 30k objects, the planner voluntarily chooses SP-GiST over
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seqscan. This is the crossover point where the index becomes
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the planner's preferred strategy.
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2. The Index Only Scan with zero heap fetches means the index
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contains all information needed — no table access required.
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3. The 75.9% pruning rate on the 2h window means only 7,188 of
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29,784 satellites need SGP4 propagation. This avoids ~22,596
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unnecessary SGP4 calls in the predict_passes() pipeline.
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4. The equatorial observer (84.3% pruned) and high-elevation
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(82.4% pruned) queries show the strongest filtering because
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the altitude and RAAN filters are most aggressive there.
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5. The 24h window only prunes 9.4% because the RAAN filter
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self-disables for full Earth rotations, leaving only the
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altitude and inclination filters active.
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