fix: mock engine sharding (was implemented for cartridge only)

After implementing cartridge sharding mock tests were mostly
useless: we didn't see how we modify SQL according to some specific
shard.

Now (in a case of the filtered buckets when we send a query to exact
shards) mock engine generates SQL for every shard. This behavior
differs from the cartridge engine that groups buckets by replicasets
first and then generated SQL for a replicaset bucket group. But the
idea of the mock engine is to detect errors but not to implement
actual Tarantool. So, lets make things simple and use this approach.

src/executor/engine/mock.rs

 use std::cell::RefCell;
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 
+use crate::collection;
 use crate::errors::QueryPlannerError;
 use crate::executor::bucket::Buckets;
 use crate::executor::engine::cartridge::cache::lru::{LRUCache, DEFAULT_CAPACITY};
@@ -10,6 +11,7 @@ use crate::executor::result::{BoxExecuteFormat, Value};
 use crate::executor::vtable::VirtualTable;
 use crate::executor::{Metadata, QueryCache};
 use crate::frontend::sql::ast::AbstractSyntaxTree;
+use crate::ir::helpers::RepeatableState;
 use crate::ir::relation::{Column, Table, Type};
 use crate::ir::value::Value as IrValue;
 use crate::ir::Plan;
@@ -219,14 +221,16 @@ impl Engine for EngineMock {
     ) -> Result<BoxExecuteFormat, QueryPlannerError> {
         let mut result = BoxExecuteFormat::new();
         let nodes = plan.get_sql_order(top_id)?;
-        let sql = plan.syntax_nodes_as_sql(&nodes, buckets)?;
 
         match buckets {
             Buckets::All => {
+                let sql = plan.syntax_nodes_as_sql(&nodes, buckets)?;
                 result.extend(cluster_exec_query(&sql))?;
             }
             Buckets::Filtered(list) => {
                 for bucket in list {
+                    let bucket_set: HashSet<u64, RepeatableState> = collection! { *bucket };
+                    let sql = plan.syntax_nodes_as_sql(&nodes, &Buckets::Filtered(bucket_set))?;
                     let temp_result = bucket_exec_query(*bucket, &sql);
                     result.extend(temp_result)?;
                 }

src/executor/tests.rs

@@ -132,7 +132,7 @@ fn linker_test() {
                 "{} {} {}",
                 r#"SELECT "test_space"."FIRST_NAME" as "FIRST_NAME""#,
                 r#"FROM "test_space""#,
-                r#"WHERE ("test_space"."id") in (SELECT COLUMN_2 as "identification_number" FROM (VALUES (2),(3)))"#,
+                r#"WHERE ("test_space"."id") in (SELECT COLUMN_1 as "identification_number" FROM (VALUES (3)))"#,
             )),
         ],
         vec![
@@ -141,7 +141,7 @@ fn linker_test() {
                 "{} {} {}",
                 r#"SELECT "test_space"."FIRST_NAME" as "FIRST_NAME""#,
                 r#"FROM "test_space""#,
-                r#"WHERE ("test_space"."id") in (SELECT COLUMN_2 as "identification_number" FROM (VALUES (2),(3)))"#,
+                r#"WHERE ("test_space"."id") in (SELECT COLUMN_1 as "identification_number" FROM (VALUES (2)))"#,
             )),
         ],
     ]);
@@ -200,7 +200,7 @@ fn union_linker_test() {
                     r#"FROM "test_space_hist""#,
                     r#"WHERE ("test_space_hist"."sys_op") > (0)"#,
                     r#") as "t1""#,
-                    r#"WHERE ("t1"."id") in (SELECT COLUMN_2 as "identification_number" FROM (VALUES (2),(3)))"#
+                    r#"WHERE ("t1"."id") in (SELECT COLUMN_1 as "identification_number" FROM (VALUES (3)))"#
                 )
             )
         ],
@@ -219,7 +219,7 @@ fn union_linker_test() {
                     r#"FROM "test_space_hist""#,
                     r#"WHERE ("test_space_hist"."sys_op") > (0)"#,
                     r#") as "t1""#,
-                    r#"WHERE ("t1"."id") in (SELECT COLUMN_2 as "identification_number" FROM (VALUES (2),(3)))"#
+                    r#"WHERE ("t1"."id") in (SELECT COLUMN_1 as "identification_number" FROM (VALUES (2)))"#
                 )
             )
         ],
@@ -475,9 +475,9 @@ fn join_linker4_test() {
                 "{} {} {} {} {}",
                 r#"SELECT t1."id" as "id" FROM "test_space" as t1"#,
                 r#"INNER JOIN"#,
-                r#"(SELECT COLUMN_2 as "r_id" FROM (VALUES (1),(2))) as t2"#,
+                r#"(SELECT COLUMN_1 as "r_id" FROM (VALUES (2))) as t2"#,
                 r#"ON (t1."id") = (t2."r_id")"#,
-                r#"and (t1."FIRST_NAME") = (SELECT COLUMN_4 as "fn" FROM (VALUES (2),(3)))"#,
+                r#"and (t1."FIRST_NAME") = (SELECT COLUMN_3 as "fn" FROM (VALUES (2),(3)))"#,
             )),
         ],
         vec![
@@ -486,9 +486,9 @@ fn join_linker4_test() {
                 "{} {} {} {} {}",
                 r#"SELECT t1."id" as "id" FROM "test_space" as t1"#,
                 r#"INNER JOIN"#,
-                r#"(SELECT COLUMN_2 as "r_id" FROM (VALUES (1),(2))) as t2"#,
+                r#"(SELECT COLUMN_1 as "r_id" FROM (VALUES (1))) as t2"#,
                 r#"ON (t1."id") = (t2."r_id")"#,
-                r#"and (t1."FIRST_NAME") = (SELECT COLUMN_4 as "fn" FROM (VALUES (2),(3)))"#,
+                r#"and (t1."FIRST_NAME") = (SELECT COLUMN_3 as "fn" FROM (VALUES (2),(3)))"#,
             )),
         ],
     ]);
@@ -545,9 +545,9 @@ fn anonymous_col_index_test() {
                 r#""test_space"."bucket_id" as "bucket_id""#,
                 r#"FROM "test_space""#,
                 r#"WHERE (("test_space"."id") in"#,
-                r#"(SELECT COLUMN_2 as "identification_number" FROM (VALUES (2),(3)))"#,
+                r#"(SELECT COLUMN_1 as "identification_number" FROM (VALUES (3)))"#,
                 r#"or ("test_space"."id") in"#,
-                r#"(SELECT COLUMN_4 as "identification_number" FROM (VALUES (2),(3))))"#,
+                r#"(SELECT COLUMN_2 as "identification_number" FROM (VALUES (3))))"#,
             )),
         ],
         vec![
@@ -562,9 +562,9 @@ fn anonymous_col_index_test() {
                 r#""test_space"."bucket_id" as "bucket_id""#,
                 r#"FROM "test_space""#,
                 r#"WHERE (("test_space"."id") in"#,
-                r#"(SELECT COLUMN_2 as "identification_number" FROM (VALUES (2),(3)))"#,
+                r#"(SELECT COLUMN_1 as "identification_number" FROM (VALUES (2)))"#,
                 r#"or ("test_space"."id") in"#,
-                r#"(SELECT COLUMN_4 as "identification_number" FROM (VALUES (2),(3))))"#,
+                r#"(SELECT COLUMN_2 as "identification_number" FROM (VALUES (2))))"#,
             )),
         ],
     ]);