Critical Description
Hi,
while working on the YCSB optimizations, I found some very weird behavior in combination with only selecting the meta().id and having it in the where clause.
For some context, I have the primary index created on the default bucket and exactly one document with the key "foo" and the content is
{"bar": "baz"}
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So the following query does not return anything:
SELECT meta().id as id FROM `default` WHERE meta().id >= 'foo' LIMIT 10;
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{
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"requestID": "b9a2e7c2-be5c-4fde-aea2-52a8980cc20a",
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"signature": {
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"id": "json"
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},
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"results": [
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],
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"status": "success",
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"metrics": {
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"elapsedTime": "4.134321ms",
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"executionTime": "4.094911ms",
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"resultCount": 0,
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"resultSize": 0
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}
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}
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Now if I remove either the where clause (or replace it with a WHERE 1=1, so the meta().id does not come up in the where clause) OR I add some other field to the select part (*, abc, whatever) it returns the correct result:
cbq> SELECT meta().id as id, * FROM `default` WHERE meta().id >= 'foo' LIMIT 10;
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{
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"requestID": "89bf9c29-7530-4091-9799-32e7f127f1cf",
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"signature": {
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"*": "*",
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"id": "json"
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},
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"results": [
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{
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"default": {
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"bar": "baz"
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},
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"id": "foo"
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}
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],
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"status": "success",
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"metrics": {
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"elapsedTime": "5.122042ms",
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"executionTime": "5.08547ms",
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"resultCount": 1,
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"resultSize": 104
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}
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}
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|
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cbq> SELECT meta().id as id FROM `default` LIMIT 10;
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{
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"requestID": "aca691fb-fc68-4477-a474-2baddfac8114",
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"signature": {
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"id": "json"
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},
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"results": [
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{
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"id": "foo"
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}
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],
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"status": "success",
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"metrics": {
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"elapsedTime": "7.229889ms",
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"executionTime": "7.193382ms",
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"resultCount": 1,
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"resultSize": 35
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}
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}
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Looks like a bug to me? Here is the explain for the broken query, maybe it is a bug in the covered index?
cbq> explain SELECT meta().id as id FROM `default` WHERE meta().id >= 'foo' LIMIT 10;
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{
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"requestID": "40980ff8-0ee3-47ab-8b74-229945a8820a",
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"signature": "json",
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"results": [
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{
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"plan": {
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"#operator": "Sequence",
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"~children": [
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{
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"#operator": "Sequence",
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"~children": [
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{
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"#operator": "IndexScan",
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"covers": [
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"cover ((meta(`default`).`id`))"
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],
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"index": "#primary",
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"index_id": "2a543447b261f63f",
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"keyspace": "default",
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"limit": "10",
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"namespace": "default",
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"spans": [
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{
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"Range": {
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"Inclusion": 1,
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"Low": [
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"\"foo\""
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]
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}
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}
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],
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"using": "gsi"
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},
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{
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"#operator": "Parallel",
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"~child": {
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"#operator": "Sequence",
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"~children": [
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{
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"#operator": "Filter",
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"condition": "(\"foo\" \u003c= cover ((meta(`default`).`id`)))"
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},
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{
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"#operator": "InitialProject",
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"result_terms": [
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{
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"as": "id",
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"expr": "cover ((meta(`default`).`id`))"
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}
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]
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},
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{
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"#operator": "FinalProject"
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}
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]
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}
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}
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]
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},
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{
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"#operator": "Limit",
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"expr": "10"
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}
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]
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},
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"text": "SELECT meta().id as id FROM `default` WHERE meta().id \u003e= 'foo' LIMIT 10"
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}
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],
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"status": "success",
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"metrics": {
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"elapsedTime": "3.646887ms",
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"executionTime": "3.61492ms",
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"resultCount": 1,
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"resultSize": 2862
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}
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}
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One more observation is that specifying only "meta()" also works:
cbq> SELECT meta() FROM `default` WHERE meta().id >= 'foo' LIMIT 10;
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{
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"requestID": "4042a422-4bd2-490e-8d79-876b16220b47",
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"signature": {
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"$1": "object"
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},
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"results": [
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{
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"$1": {
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"cas": 408901317885952,
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"flags": 0,
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"id": "foo",
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"type": "json"
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}
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}
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],
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"status": "success",
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"metrics": {
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"elapsedTime": "4.393678ms",
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"executionTime": "4.358975ms",
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"resultCount": 1,
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"resultSize": 173
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}
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}
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