Add tests for multipart HASH indexes.

Derive some tests for multipart HASH indexes
from the original implementation by A. Demakov
before dropping the branch.

test/big/hash_multipart.result

+insert into t27 values (0, 'foo', 0, '', 1)
+Insert OK, 1 row affected
+insert into t27 values (0, 'foo', 1, '', 1)
+Insert OK, 1 row affected
+insert into t27 values (1, 'foo', 0, '', 2)
+Insert OK, 1 row affected
+insert into t27 values (1, 'foo', 1, '', 2)
+Insert OK, 1 row affected
+insert into t27 values (0, 'bar', 0, '', 3)
+Insert OK, 1 row affected
+insert into t27 values (0, 'bar', 1, '', 3)
+Insert OK, 1 row affected
+insert into t27 values (1, 'bar', 0, '', 4)
+Insert OK, 1 row affected
+insert into t27 values (1, 'bar', 1, '', 4)
+Insert OK, 1 row affected
+insert into t27 values (1, 'bar', 1, '', 5)
+An error occurred: ER_TUPLE_FOUND, 'Duplicate key exists in unique index 0'
+lua  function box.select_all(space)     space = tonumber(space)     local result = {}         for k, v in box.space[space]:pairs() do             table.insert(result, v)     end     return unpack(result) end 
+---
+...
+call box.select_all('27')
+Found 8 tuples:
+[0, 'bar', 0, '', 3]
+[0, 'bar', 1, '', 3]
+[0, 'foo', 0, '', 1]
+[0, 'foo', 1, '', 1]
+[1, 'bar', 0, '', 4]
+[1, 'bar', 1, '', 4]
+[1, 'foo', 0, '', 2]
+[1, 'foo', 1, '', 2]
+lua box.select(27, 0, 1, 'foo', 0)
+---
+ - 1: {'foo', 0, '', 2}
+...
+lua box.select(27, 0, 1, 'bar', 0)
+---
+ - 1: {'bar', 0, '', 4}
+...
+lua box.select(27, 0, 1, 'foo')
+---
+error: 'Invalid key part count in an exact match (expected 3, got 2)'
+...
+lua box.select(27, 0, 1, 'foo', 0, 0)
+---
+error: 'Invalid key part count (expected [0..3], got 4)'
+...
+lua box.select(27, 0, 1, 'foo', 'baz')
+---
+error: 'Supplied key field type does not match index type: expected u32'
+...
+lua box.select(27, 1, 1, 4)
+---
+ - 1: {'bar', 1, '', 4}
+...
+lua box.select(27, 1, 1, 5)
+---
+...
+lua box.select(27, 1, 1)
+---
+error: 'Invalid key part count in an exact match (expected 2, got 1)'
+...
+lua box.select(27, 1, 1, 'baz')
+---
+error: 'Supplied key field type does not match index type: expected u32'
+...
+lua box.space[27]:truncate()
+---
+...
+lua box.space[27]:len()
+---
+ - 0
+...

test/big/hash_multipart.test

+# encoding: tarantool
+#
+
+# insert rows
+exec sql "insert into t27 values (0, 'foo', 0, '', 1)"
+exec sql "insert into t27 values (0, 'foo', 1, '', 1)"
+exec sql "insert into t27 values (1, 'foo', 0, '', 2)"
+exec sql "insert into t27 values (1, 'foo', 1, '', 2)"
+exec sql "insert into t27 values (0, 'bar', 0, '', 3)"
+exec sql "insert into t27 values (0, 'bar', 1, '', 3)"
+exec sql "insert into t27 values (1, 'bar', 0, '', 4)"
+exec sql "insert into t27 values (1, 'bar', 1, '', 4)"
+# try to insert a row with a duplicate key
+exec sql "insert into t27 values (1, 'bar', 1, '', 5)"
+
+# output all rows
+lua_code = """
+function box.select_all(space)
+    space = tonumber(space)
+    local result = {}
+        for k, v in box.space[space]:pairs() do
+            table.insert(result, v)
+    end
+    return unpack(result)
+end
+"""
+exec admin "lua " + lua_code.replace('\n', ' ')
+sql.sort = True
+exec sql "call box.select_all('27')"
+sql.sort = False
+
+# primary index select
+exec admin "lua box.select(27, 0, 1, 'foo', 0)"
+exec admin "lua box.select(27, 0, 1, 'bar', 0)"
+# primary index slect with missing part
+exec admin "lua box.select(27, 0, 1, 'foo')"
+# primary index slect with extra part
+exec admin "lua box.select(27, 0, 1, 'foo', 0, 0)"
+# primary index select with wrong type
+exec admin "lua box.select(27, 0, 1, 'foo', 'baz')"
+
+# secondary index select
+exec admin "lua box.select(27, 1, 1, 4)"
+# secondary index select with no such key
+exec admin "lua box.select(27, 1, 1, 5)"
+# secondary index select with missing part
+exec admin "lua box.select(27, 1, 1)"
+# secondary index select with wrong type
+exec admin "lua box.select(27, 1, 1, 'baz')"
+
+# cleanup
+exec admin "lua box.space[27]:truncate()"
+exec admin "lua box.space[27]:len()"

test/big/tarantool.cfg

@@ -375,3 +375,22 @@ space[26].index[1].type = "HASH"
 space[26].index[1].unique = true
 space[26].index[1].key_field[0].fieldno = 0
 space[26].index[1].key_field[0].type = "NUM"
+
+# Multi-part hash
+space[27].enabled = 1
+
+space[27].index[0].type = HASH
+space[27].index[0].unique = 1
+space[27].index[0].key_field[0].fieldno = 0
+space[27].index[0].key_field[0].type = NUM
+space[27].index[0].key_field[1].fieldno = 1
+space[27].index[0].key_field[1].type = STR
+space[27].index[0].key_field[2].fieldno = 2
+space[27].index[0].key_field[2].type = NUM
+
+space[27].index[1].type = HASH
+space[27].index[1].unique = 1
+space[27].index[1].key_field[0].fieldno = 2
+space[27].index[1].key_field[0].type = NUM
+space[27].index[1].key_field[1].fieldno = 4
+space[27].index[1].key_field[1].type = NUM