Index not improve speed in couchbase 4.5

问题

I have below query

SELECT day,count(DISTINCT campaignId) campaigns
FROM Inheritx use index(daily_type_1)
where _type='DailyCampaignUsage'
group by day

I have below index

 `CREATE INDEX `daily_type_1` ON `Inheritx` 
(`_type`,`day`,(distinct (`campaignId`))) WHERE (`_type` = "DailyCampaignUsage")`

it is taking 3s and I habe 52k data whare _type= "DailyCampaignUsage"

how I Can improve it's speed ?

回答1:

Modify your index as follows.

CREATE INDEX `daily_type_1` ON `Inheritx` (campaignId,`day`)
WHERE (`_type` = "DailyCampaignUsage");

Keep the index in this answer. Modify your query as follows.

SELECT day,count(DISTINCT campaignId) campaigns
FROM Inheritx use index(daily_type_1)
where _type='DailyCampaignUsage'
and campaignId is not null
group by day;

来源：https://stackoverflow.com/questions/41544159/index-not-improve-speed-in-couchbase-4-5