crud doesn't build key from conditions #402
Description
Let's consider the space with multipart unique key. One can be obtained from the playground with the following patch.
diff --git a/doc/playground.lua b/doc/playground.lua
index d4e547f..86293a7 100755
--- a/doc/playground.lua
+++ b/doc/playground.lua
@@ -75,6 +75,7 @@ box.once('customers', function()
box.space.customers:create_index('primary_index', {
parts = {
{field = 1, type = 'unsigned'},
+ {field = 4, type = 'number'},
},
})
box.space.customers:create_index('bucket_id', {
@@ -83,15 +84,12 @@ box.once('customers', function()
},
unique = false,
})
- box.space.customers:create_index('age', {
- parts = {
- {field = 4, type = 'number'},
- },
- unique = false,
- })
-- Fill the space.
box.space.customers:insert({1, 477, 'Elizabeth', 12})
+ box.space.customers:insert({1, 477, 'Elizabeth', 13})
+ box.space.customers:insert({1, 477, 'Elizabeth', 14})
+ box.space.customers:insert({1, 477, 'Elizabeth', 15})
box.space.customers:insert({2, 401, 'Mary', 46})
box.space.customers:insert({3, 2804, 'David', 33})
box.space.customers:insert({4, 1161, 'William', 81})
If the conditions are specified with index, it is a simple "get by key" procedure.
tarantool> crud.select('customers', {{'==', 'primary_index', {1, 15} }})
---
- metadata: [{'name': 'id', 'type': 'unsigned'}, {'name': 'bucket_id', 'type': 'unsigned'},
{'name': 'name', 'type': 'string'}, {'name': 'age', 'type': 'number'}]
rows:
- [1, 477, 'Elizabeth', 15]
- null
...
tarantool> crud.stats()
---
- spaces:
customers:
select:
details:
tuples_lookup: 1
tuples_fetched: 1
...Stats say that we have found the requested data without any scanning.
If the conditions are specified with fields, it is a scan over all tuples satisfying the first condition.
tarantool> crud.select('customers', {{'==', 'id', 1}, {'==', 'age', 15}})
---
- metadata: [{'name': 'id', 'type': 'unsigned'}, {'name': 'bucket_id', 'type': 'unsigned'},
{'name': 'name', 'type': 'string'}, {'name': 'age', 'type': 'number'}]
rows:
- [1, 477, 'Elizabeth', 15]
- null
...
tarantool> crud.stats()
---
- spaces:
customers:
select:
details:
tuples_lookup: 4
tuples_fetched: 1
...Stats say that we have scrolled through all id: 1 tuples until we have filtered ones satisfying age: 15 condition.
The same scan is performed in case of crud.select('customers', {{'==', 'id', 1}, {'==', 'age', 12}}): the module does not treat age: 12 condition as the part of the index both to start and to stop.