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andrew-farriesandrew-farries
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Fix read_schema function for multi-column foreign key constaints (#476)
Update the query used by `read_schema` to fetch foreign key information. This fixes the problem of `columns` and `referencedColumns` containing duplicate entries for multi-column foreign keys. For a foreign key defined like `"fk_sellers" FOREIGN KEY (sellers_name, sellers_zip) REFERENCES sellers(name, zip)` the change in behaviour is as follows: Before: ```json { ... "foreignKeys": { "fk_sellers": { "name": "fk_sellers", "columns": [ "sellers_name", "sellers_zip", "sellers_name", "sellers_zip" ], "referencedTable": "sellers", "referencedColumns": [ "name", "zip", "name", "zip" ], "onDelete": "NO ACTION" } }, } ``` After: ```json { ... "foreignKeys": { "fk_sellers": { "name": "fk_sellers", "columns": [ "sellers_name", "sellers_zip" ], "referencedTable": "sellers", "referencedColumns": [ "name", "zip" ], "onDelete": "NO ACTION" } }, } ``` The solution here is to perform grouping and array aggregation of the referencing table's columns before the join to the referenced table's columns. Fixes #475
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‎pkg/state/init.sql

Lines changed: 36 additions & 25 deletions
Original file line numberDiff line numberDiff line change
@@ -205,31 +205,42 @@ BEGIN
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'columns', fk_details.columns,
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'referencedTable', fk_details.referencedTable,
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'referencedColumns', fk_details.referencedColumns,
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'onDelete', fk_details.onDelete
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)), '{}'::json)
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FROM (SELECT fk_constraint.conname,
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array_agg(fk_attr.attname ORDER BY fk_constraint.conkey::int[]) AS columns,
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fk_cl.relname AS referencedTable,
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array_agg(ref_attr.attname ORDER BY fk_constraint.confkey::int[]) AS referencedColumns,
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CASE
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WHEN fk_constraint.confdeltype = 'a' THEN 'NO ACTION'
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WHEN fk_constraint.confdeltype = 'r' THEN 'RESTRICT'
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WHEN fk_constraint.confdeltype = 'c' THEN 'CASCADE'
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WHEN fk_constraint.confdeltype = 'd' THEN 'SET DEFAULT'
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WHEN fk_constraint.confdeltype = 'n' THEN 'SET NULL'
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END as onDelete
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FROM pg_constraint AS fk_constraint
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INNER JOIN pg_class fk_cl ON fk_constraint.confrelid = fk_cl.oid
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INNER JOIN pg_attribute fk_attr
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ON fk_attr.attrelid = fk_constraint.conrelid AND
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fk_attr.attnum = ANY (fk_constraint.conkey)
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INNER JOIN pg_attribute ref_attr
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ON ref_attr.attrelid = fk_constraint.confrelid AND
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ref_attr.attnum = ANY (fk_constraint.confkey)
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WHERE fk_constraint.conrelid = t.oid
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AND fk_constraint.contype = 'f'
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GROUP BY fk_constraint.conname, fk_cl.relname,
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fk_constraint.confdeltype) AS fk_details)
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'onDelete', fk_details.onDelete)), '{}'::json)
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FROM (SELECT
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fk_info.conname as conname,
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fk_info.columns as columns,
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fk_info.relname as referencedTable,
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array_agg(ref_attr.attname ORDER BY ref_attr.attname) AS referencedColumns,
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CASE
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WHEN fk_info.confdeltype = 'a' THEN 'NO ACTION'
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WHEN fk_info.confdeltype = 'r' THEN 'RESTRICT'
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WHEN fk_info.confdeltype = 'c' THEN 'CASCADE'
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WHEN fk_info.confdeltype = 'd' THEN 'SET DEFAULT'
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WHEN fk_info.confdeltype = 'n' THEN 'SET NULL'
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END as onDelete
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FROM (
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SELECT
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fk_constraint.conname,
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fk_constraint.conrelid,
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fk_constraint.confrelid,
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fk_constraint.confkey,
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fk_cl.relname,
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fk_constraint.confdeltype,
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array_agg(fk_attr.attname ORDER BY fk_attr.attname) AS columns
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FROM pg_constraint AS fk_constraint
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INNER JOIN pg_class fk_cl ON fk_constraint.confrelid = fk_cl.oid -- join the referenced table
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INNER JOIN pg_attribute fk_attr ON
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fk_attr.attrelid = fk_constraint.conrelid AND
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fk_attr.attnum = any(fk_constraint.conkey) -- join the columns of the referencing table
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WHERE fk_constraint.conrelid = t.oid
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AND fk_constraint.contype = 'f'
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GROUP BY fk_constraint.conrelid, fk_constraint.conname, fk_constraint.confrelid, fk_cl.relname, fk_constraint.confkey, fk_constraint.confdeltype
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) AS fk_info
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INNER JOIN pg_attribute ref_attr ON
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ref_attr.attrelid = fk_info.confrelid AND
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ref_attr.attnum = any(fk_info.confkey) -- join the columns of the referenced table
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GROUP BY fk_info.conname, fk_info.conrelid, fk_info.columns, fk_info.confrelid, fk_info.confdeltype, fk_info.relname
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) AS fk_details)
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)), '{}'::json)
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FROM pg_class AS t
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INNER JOIN pg_namespace AS ns ON t.relnamespace = ns.oid

‎pkg/state/state_test.go

Lines changed: 73 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -755,6 +755,79 @@ func TestReadSchema(t *testing.T) {
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},
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},
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},
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{
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name: "multicolumn foreign key constraint",
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createStmt: `CREATE TABLE products(
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customer_id INT NOT NULL,
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product_id INT NOT NULL,
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PRIMARY KEY(customer_id, product_id));
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CREATE TABLE orders(
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customer_id INT NOT NULL,
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product_id INT NOT NULL,
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CONSTRAINT fk_customer_product FOREIGN KEY (customer_id, product_id) REFERENCES products (customer_id, product_id));`,
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wantSchema: &schema.Schema{
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Name: "public",
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Tables: map[string]schema.Table{
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"products": {
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Name: "products",
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Columns: map[string]schema.Column{
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"customer_id": {
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Name: "customer_id",
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Type: "integer",
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Nullable: false,
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},
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"product_id": {
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Name: "product_id",
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Type: "integer",
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Nullable: false,
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},
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},
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PrimaryKey: []string{"customer_id", "product_id"},
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Indexes: map[string]schema.Index{
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"products_pkey": {
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Name: "products_pkey",
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Unique: true,
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Columns: []string{"customer_id", "product_id"},
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Method: string(migrations.OpCreateIndexMethodBtree),
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Definition: "CREATE UNIQUE INDEX products_pkey ON public.products USING btree (customer_id, product_id)",
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},
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},
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ForeignKeys: map[string]schema.ForeignKey{},
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CheckConstraints: map[string]schema.CheckConstraint{},
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UniqueConstraints: map[string]schema.UniqueConstraint{},
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},
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"orders": {
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Name: "orders",
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Columns: map[string]schema.Column{
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"customer_id": {
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Name: "customer_id",
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Type: "integer",
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Nullable: false,
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},
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"product_id": {
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Name: "product_id",
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Type: "integer",
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Nullable: false,
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},
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},
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PrimaryKey: []string{},
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Indexes: map[string]schema.Index{},
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ForeignKeys: map[string]schema.ForeignKey{
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"fk_customer_product": {
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Name: "fk_customer_product",
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Columns: []string{"customer_id", "product_id"},
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ReferencedTable: "products",
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ReferencedColumns: []string{"customer_id", "product_id"},
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OnDelete: "NO ACTION",
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},
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},
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CheckConstraints: map[string]schema.CheckConstraint{},
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UniqueConstraints: map[string]schema.UniqueConstraint{},
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},
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},
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},
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},
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{
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name: "multi-column index",
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createStmt: "CREATE TABLE public.table1 (a text, b text); CREATE INDEX idx_ab ON public.table1 (a, b);",

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