如何通过以下方式优化Couchbase NQ1L订单
考虑以下用例: 索引如何通过以下方式优化Couchbase NQ1L订单,couchbase,Couchbase,考虑以下用例: 索引 CREATE INDEX `type-index`ON bucket( type, createdAt) WHERE type='someType'; 查询(性能相当好) 执行时间:14.51毫秒 一个查询(执行得非常糟糕) 执行:1m 这里有一个解释 [ { "plan": { "#operator": "Sequence", "~children": [ { "#operator": "Seque
CREATE INDEX `type-index`ON bucket( type, createdAt) WHERE type='someType';
查询(性能相当好)
执行时间:14.51毫秒
一个查询(执行得非常糟糕)
执行:1m
这里有一个解释
[
{
"plan": {
"#operator": "Sequence",
"~children": [
{
"#operator": "Sequence",
"~children": [
{
"#operator": "IndexScan",
"index": "type-index",
"index_id": "ee6b75813c26795c",
"keyspace": "bucket",
"namespace": "default",
"spans": [
{
"Range": {
"High": [
"successor(\"someType\")"
],
"Inclusion": 1,
"Low": [
"\"someType\""
]
}
}
],
"using": "gsi"
},
{
"#operator": "Parallel",
"~child": {
"#operator": "Sequence",
"~children": [
{
"#operator": "Fetch",
"as": "a",
"keyspace": "bucket",
"namespace": "default"
},
{
"#operator": "Filter",
"condition": "((`a`.`_type`) = \"someType\")"
},
{
"#operator": "InitialProject",
"result_terms": [
{
"expr": "`a`",
"star": true
}
]
}
]
}
}
]
},
{
"#operator": "Order",
"limit": "10",
"offset": "10",
"sort_terms": [
{
"desc": true,
"expr": "(`a`.`createdAt`)"
}
]
},
{
"#operator": "Offset",
"expr": "10"
},
{
"#operator": "Limit",
"expr": "10"
},
{
"#operator": "FinalProject"
}
]
},
"text": "SELECT a.* FROM `bucket` a WHERE a.type='someType' ORDER BY a.createdAt DESC IMIT 10 OFFSET 10"
}
]
该存储桶包含170万个文档。是否有任何方法可以提高ORDER BY的性能?值
createdAt
是unix时间戳(数字)解决方案是创建如下索引:
CREATE INDEX `type-index` ON bucket ( -createdAt ) WHERE type='sometType';
以及查询
SELECT a.*
FROM `bucket` a
WHERE type='someType'
AND -createdAt IS NOT NULL
ORDER BY -createdAt
LIMIT 10 OFFSET 10;
基本上,解决方案是创建正确的对流索引,并确保您正在使用它。计划中提供了对DESC的更好支持,并将在下一版本中提供。目前,上述解决方案应该可以正常工作。
CREATE INDEX `type-index` ON bucket ( -createdAt ) WHERE type='sometType';
SELECT a.*
FROM `bucket` a
WHERE type='someType'
AND -createdAt IS NOT NULL
ORDER BY -createdAt
LIMIT 10 OFFSET 10;