Put uuids in the vae and eav index

[dwwoelfel]

We only put refs in the vae and eav indexes so we know that the value will be a uuid. This PR stores those uuids as actual uuids in the index itself.

This makes the indexes take up less space (they're about 30% smaller).

The big change is that now we can use vae instead of eav when we do a join on a ref, which saves us doing an expensive json->uuid conversion in the join filter. Here's a simple example:

{:books {:where {:category "western" :author :eid/elmer-kelton}}}

That generates two ctes:

with m_0 as (
  select entity_id as m_0_eid from triples t0 where attr_id = :category-eid and value = "western"
),
m_1 as (
  select m_0.*, entity_id as m_1_eid from triples t1 where value = :eid/elmer-kelton and m_0.m_0_eid = json_to_uuid(value)
)

If we use the eav index for m_1, the v is at the end of the index. Postgres does a nested loop and filters the join on entity_id = json_to_uuid(value). It looks something like this:

    ->  Nested Loop
          Join Filter: (t0.entity_id = ((t1.value ->> 0))::uuid)
          Rows Removed by Join Filter: N
          ->  Index Scan using ave_index on triples t0
                Index Cond: (attr_id = :category-eid) AND (value = '"western"'::jsonb)
          ->  Index Scan using eav_uuid_index on triples t1
                Index Cond: ((entity_id = :eid) AND (attr_id = :author-eid))

If we use the vae index for m_1, then the v is at the start of the index and postgres will use that in the index cond instead of the less efficient join filter. It looks something like this:

    ->  Nested Loop 
          ->  Index Scan using ave_index on triples t0 
                Index Cond: (attr_id = :category-eid) AND (value = '"western"'::jsonb)
          ->  Index Scan using vae_uuid_index on triples t1
                Index Cond: ((((value ->> 0))::uuid = t0.entity_id) AND (attr_id = :author-eid) AND (entity_id =:eid))

((value ->> 0))::uuid is already in the index, so we never have to do any json->uuid conversion at all in the query itself. We avoid the expensive join filter, which in my backtesting makes queries much faster.

We also don't have to carry around the match_x_x_value_uuid any more. Instead of value_uuid, we track is_ref_value so that we know to convert it from a string to a uuid in sql-row->triple.

Results from the backtest:

I'm not super concerned about the first two queries that got worse because they're not slower if I enable pg hints.

:old-explain	:new-explain	:improvement
513	2075	-1562
676	1578	-901
393	574	-181
489	595	-105
286	375	-89
3	86	-83
6	87	-80
4	83	-78
5	84	-78
5	84	-78
6	84	-78
341	418	-76
5	82	-76
5	79	-74
306	379	-73
5	70	-65
99	164	-64
290	351	-61
110	171	-60
280	340	-60
117	175	-58
134	192	-58
117	173	-56
80	135	-55
4	59	-55
144	198	-54
5	58	-53
4	58	-53
110	163	-53
125	177	-52
4	56	-51
115	166	-51
131	181	-49
238	288	-49
156	205	-49
139	188	-49
4	53	-49
87	136	-48
445	494	-48
4	53	-48
457	502	-45
136	181	-44
110	153	-43
187	230	-43
134	177	-42
100	143	-42
112	154	-41
58	99	-41
22	63	-41
274	316	-41
119	160	-41
22	63	-41
87	128	-40
134	173	-38
120	158	-38
20	58	-38
379	417	-38
129	167	-38
103	139	-36
112	148	-35
125	159	-34
18	52	-33
113	147	-33
103	136	-33
109	141	-32
82	113	-31
170	201	-30
90	121	-30
196	226	-30
113	141	-28
73	100	-27
96	123	-27
157	184	-26
79	105	-26
205	231	-25
7	33	-25
29	54	-24
277	302	-24
82	106	-24
74	97	-23
278	302	-23
155	178	-22
350	371	-21
8	29	-20
299	320	-20
17	38	-20
76	97	-20
72	93	-20
10	30	-19
149	167	-18
20	38	-18
66	84	-18
19	37	-18
246	264	-17
42	59	-17
96	113	-17
70	88	-17
82	100	-17
36	53	-16
29	45	-15
6	21	-15
4	19	-15
3	18	-15
9	24	-15
38	53	-15
120	135	-15
61	76	-15
3	18	-14
54	69	-14
98	113	-14
93	108	-14
113	127	-14
3	17	-14
3	17	-13
7	20	-12
42	55	-12
315	328	-12
220	232	-11
4	15	-11
10	21	-11
37	47	-10
39	49	-10
28	38	-9
44	54	-9
21	31	-9
43	53	-9
10	20	-9
33	42	-9
26	35	-9
30	39	-8
72	81	-8
47	55	-8
50	58	-8
53	61	-7
4	12	-7
44	51	-7
52	59	-6
37	44	-6
24	31	-6
56	63	-6
97	103	-6
57	64	-6
80	87	-6
48	54	-5
128	134	-5
51	57	-5
3	8	-5
40	45	-5
3	8	-4
120	125	-4
28	33	-4
50	55	-4
129	133	-4
2	6	-4
20	24	-4
21	25	-4
20	24	-4
12	16	-3
40	44	-3
47	51	-3
174	178	-3
19	22	-3
9	12	-3
17	20	-3
27	31	-3
17	21	-3
9	12	-3
18	21	-3
12	15	-3
41	44	-3
132	135	-3
19	22	-2
30	33	-2
9	12	-2
36	38	-2
18	21	-2
9	11	-2
13	15	-2
8	10	-2
4	6	-1
11	13	-1
44	45	-1
29	31	-1
10	12	-1
14	15	-1
2	4	-1
99	101	-1
15	16	-1
10	12	-1
40	41	-1
14	15	-1
27	28	-1
73	74	-1
6	8	-1
8	9	-1
49	50	-1
15	16	-1
20	21	-1
13	14	-1
12	13	-1
6	7	-1
6	7	-1
4	5	-1
22	23	-1
33	34	0
6	7	0
14	15	0
7	8	0
1	2	0
16	16	0
57	58	0
6	6	0
14	15	0
11	12	0
7	8	0
1	1	0
2	2	0
2	2	0
4	5	0
18	19	0
16	16	0
1	2	0
4	5	0
19	20	0
10	11	0
2	2	0
2	2	0
4	5	0
21	22	0
4	4	0
3	3	0
2	3	0
8	8	0
8	8	0
1	1	0
30	31	0
6	7	0
23	23	0
7	8	0
4	4	0
7	8	0
6	7	0
1	1	0
2	2	0
4	5	0
8	8	0
18	18	0
1	1	0
1	1	0
2	2	0
1	1	0
29	29	0
1	1	0
1	1	0
2	2	0
10	10	0
4	4	0
2	2	0
3	4	0
1	1	0
1	1	0
1	1	0
1	1	0
12	12	0
1	1	0
1	2	0
1	1	0
13	13	0
8	8	0
1	2	0
3	4	0
0	1	0
0	0	0
1	1	0
15	15	0
28	28	0
1	1	0
9	10	0
18	18	0
2	2	0
2	2	0
1	1	0
2	2	0
1	1	0
30000	30000	0
30000	30000	0
30000	30000	0
1	1	0
5	5	0
2	2	0
56	56	0
5	5	0
2	2	0
1	1	0
1	1	0
9	9	0
1	1	0
2	2	0
7	7	0
2	2	0
27	27	0
3	2	0
1	1	0
7	7	0
3	3	0
5	5	0
5	5	0
14	14	0
6	6	0
10	10	0
2	1	0
34	34	0
23	23	0
2	2	0
4	3	0
7	7	0
1	1	0
17	16	0
2	1	0
4	3	0
5	4	0
6	6	0
1	1	0
16	15	0
3	2	0
13	13	0
2	1	0
2	2	0
1	1	0
10	10	0
1	1	0
9	9	0
4	3	0
5	5	0
2	1	0
7	7	0
5	5	0
2	2	0
3	3	0
7	7	0
3	3	0
8	7	0
1	1	0
7	7	0
3	2	0
8	8	0
7	6	0
6	5	0
22	21	0
7	7	0
14	14	0
14	13	0
7	7	0
3	2	0
7	7	0
4	3	0
53	52	0
6	5	0
9	8	0
13	12	0
2	1	0
21	21	0
7	6	0
8	7	0
17	17	0
9	8	0
3	2	0
5	4	0
19	18	0
7	6	0
19	18	0
4	4	0
3	2	0
2	1	0
5	4	0
14	13	0
8	7	0
11	10	0
3	2	0
11	10	0
27	26	0
40	39	0
3	2	0
3	2	0
2	1	0
2	1	1
6	5	1
4	3	1
6	5	1
3	2	1
5	4	1
3	2	1
4	3	1
4	3	1
37	35	1
10	8	1
4	2	1
3	2	1
8	6	1
6	5	1
4	3	1
7	6	1
5	4	1
31	30	1
10	8	1
6	5	1
62	61	1
4	3	1
5	3	1
13	12	1
28	27	1
9	7	1
4	2	1
4	3	1
9	8	1
3	2	1
9	7	1
11	10	1
51	50	1
5	3	1
58	57	1
11	10	1
8	6	1
15	14	1
7	5	1
23	22	1
10	9	1
19	18	1
4	3	1
99	98	1
6	5	1
8	7	1
6	4	1
12	10	1
4	2	1
28	26	1
24	23	1
47	46	1
12	10	1
15	13	1
4	2	1
6	4	1
6	4	1
27	25	2
4	2	2
20	18	2
10	8	2
24	22	2
5	2	2
9	7	2
6	4	2
17	15	2
13	11	2
32	30	2
11	8	2
16	13	2
18	16	2
8	6	2
13	11	2
19	16	2
25	22	2
566	563	2
14	11	2
10	7	2
20	17	2
61	58	2
11	8	2
23	20	2
17	14	2
21	18	2
12	9	3
25	22	3
16	13	3
22	19	3
41	37	3
9	6	3
38	34	3
12	8	3
38	34	3
25	21	3
16	12	3
38	35	3
57	54	3
23	19	3
9	5	3
20	16	4
12	8	4
45	41	4
56	52	4
13	8	4
24	19	4
36	31	4
9	5	4
23	19	4
56	51	4
22	17	4
62	57	4
30	26	4
22	17	4
20	15	4
91	86	4
14	9	4
74	69	4
39	34	4
43	38	4
50	45	4
131	126	4
12	7	5
19	14	5
31	26	5
22	17	5
26	21	5
47	41	5
20	15	5
188	182	5
44	39	5
39	34	5
47	41	6
70	64	6
55	49	6
46	40	6
70	63	6
52	45	6
44	38	6
45	38	6
62	55	6
28	21	7
42	35	7
16	9	7
68	61	7
57	50	7
13	6	7
47	40	7
58	50	7
46	38	7
37	29	8
45	37	8
43	34	8
34	26	8
43	34	9
16	7	9
57	48	9
16	7	9
36	26	9
166	156	9
17	7	9
46	36	9
18	8	10
57	47	10
56	45	11
143	132	11
41	30	11
40	28	11
25	12	12
67	55	12
43	30	12
55	42	12
25	13	12
72	59	12
42	29	12
23	10	12
27	14	13
131	117	13
39	26	13
23	9	13
43	29	13
51	37	14
176	161	14
89	73	15
22	6	15
114	98	15
27	11	15
40	24	15
30	14	16
214	198	16
84	67	16
75	58	17
85	66	18
24	5	18
31	12	18
88	69	19
134	115	19
220	200	19
40	20	20
48	27	20
62	41	20
76	55	21
130	109	21
33	12	21
84	63	21
103	81	21
193	171	22
105	82	22
75	52	22
41	19	22
101	78	22
100	77	22
55	32	23
81	58	23
216	193	23
97	73	23
134	110	23
77	53	23
150	126	23
54	30	24
146	121	24
160	134	25
113	87	26
47	19	27
53	24	29
121	91	30
209	179	30
196	165	30
62	31	30
59	29	30
389	358	31
102	69	33
105	72	33
81	48	33
73	38	34
228	190	37
202	162	39
81	41	40
81	41	40
107	66	41
500	459	41
84	42	41
330	287	42
134	91	42
146	101	44
127	82	44
87	42	45
85	39	45
401	356	45
347	301	46
704	658	46
599	553	46
251	204	46
78	31	46
287	240	47
97	49	47
134	87	47
89	41	47
253	205	48
117	69	48
99	50	48
426	377	48
355	306	49
213	164	49
116	66	50
228	177	50
97	46	51
205	153	51
70	18	51
124	73	51
95	43	52
126	73	52
95	42	52
97	44	53
179	125	53
311	257	54
340	285	54
142	87	54
224	169	55
307	249	57
100	42	58
82	22	59
432	372	59
146	85	60
108	47	61
107	41	65
329	263	66
162	94	68
318	249	68
356	287	69
236	166	69
238	167	70
361	290	70
148	77	71
447	372	74
234	158	76
245	168	77
428	349	78
598	519	79
128	45	82
181	96	85
247	161	86
230	141	89
140	48	92
160	67	92
365	269	96
378	281	96
324	224	99
123	23	100
288	187	101
169	65	103
206	100	105
308	202	106
876	767	109
566	456	110
225	114	111
197	85	111
359	246	113
159	44	114
240	125	115
377	256	120
344	220	123
234	110	124
240	116	124
215	89	125
212	85	126
207	79	127
208	80	128
211	83	128
315	184	131
211	80	131
171	38	132
171	38	133
214	79	135
173	37	135
437	301	135
185	49	136
219	82	137
216	78	138
251	111	140
543	402	140
179	37	141
215	73	142
227	84	142
234	88	145
228	81	147
694	545	148
411	262	149
239	87	152
237	82	155
240	85	155
244	81	163
403	238	164
812	638	173
665	491	174
597	407	190
321	120	200
721	508	212
280	54	226
476	239	237
353	115	238
328	87	240
1463	1204	258
724	455	268
701	398	302
526	159	367
1294	924	369
496	122	374
462	86	376
1313	927	386
590	196	393
1347	945	402
1339	907	432
595	144	451
674	220	454
1435	942	492
1278	781	496
740	221	518
696	174	522
742	189	552
919	227	691
1039	265	773
1068	285	782
1090	287	802
1090	283	807
1311	473	838
1175	334	840
1129	282	847
1163	295	867
1246	340	906
2019	460	1558
2467	868	1599
2404	717	1686
3170	1395	1774
3178	1291	1886
2624	736	1887
4255	2099	2155
2907	710	2196
2828	574	2253
3258	738	2519
3374	730	2644
4362	1633	2728
4320	1567	2752
4321	1505	2815
4376	1556	2819
4451	1620	2830
4405	1551	2853
4421	1567	2853
4366	1469	2896
4468	1550	2918
4458	1532	2925
4478	1490	2987
4550	1547	3002
4550	1540	3009
4644	1611	3033
4547	1510	3037
4675	1606	3069
4725	1641	3084
4718	1630	3087
4685	1593	3091
4733	1618	3115
4645	1523	3121
4629	1507	3122
4780	1653	3126
4716	1581	3135
4746	1601	3145
4998	1851	3146
4697	1549	3147
4679	1526	3152
4763	1605	3158
4708	1531	3177
4700	1512	3188
4759	1569	3189
4723	1533	3189
4672	1479	3193
4826	1627	3198
4774	1574	3199
4685	1482	3202
4748	1540	3207
4833	1621	3211
4710	1496	3213
4725	1506	3219
4745	1520	3224
4752	1523	3229
4771	1537	3233
4815	1578	3237
4799	1561	3238
4780	1531	3249
4743	1490	3252
4734	1481	3252
4788	1533	3255
4794	1524	3269
4939	1660	3279
4860	1572	3287
4832	1534	3297
4768	1467	3300
4795	1461	3333
4918	1549	3368
4968	1551	3417
5006	1451	3555
4121	247	3874
5340	1347	3993
6845	1556	5289
10090	2132	7958

Deployment plan

1. Merge into main
2. Add the indexes concurrently:

create or replace function public.json_uuid_to_uuid(v jsonb) returns uuid
  language sql
  parallel safe
  immutable
  as $$
   select (v->>0)::uuid
  end;
$$;

create index concurrently if not exists vae_uuid_index
  on triples(app_id, public.json_uuid_to_uuid(value), attr_id, entity_id)
  where vae;

create unique index concurrently if not exists eav_uuid_index
  on triples(app_id, entity_id, attr_id, public.json_uuid_to_uuid(value))
  where eav;

3. Run the migration
4. Deploy the code
5. Drop ave_index and eav_index in a followup PR (which also needs to happen concurrently)

[github-actions]

View Vercel preview at instant-www-js-vae-uuids-jsv.vercel.app.

[dwwoelfel]

This also fixes a bug in the topics, where we weren't removing vae triples from the topics symbol map. (see https://github.com/jsventures/instant/pull/827 for more explanation).

I don't think we actually encounter the bug in prod because we always invalidate the id field on updates (will be fixed by #739). What could happen when we fix the id bug: say you have a query that orders on order-field, if you update order-field on an existing entity outside of the result set so that it should be in the result set, we won't invalidate the query because our topic is looking at a specific entity (e.g. [:eid :order-field _]). With this change, the topic will be [_ :order-field :_], so the query will get invalidated. Again, it's not a problem now because we have the topic [_ :id _] and it gets invalidated on any change.

[stopachka]

😍

[stopachka]

oh heck yeah!

[stopachka]

Genius find @dwwoelfel!