feat: add postgres index , impl Migrator GetIndexes func (#113)

* feat: add postgres index

* fix: change  index sql

* fix: remove code base code review

* fix: remove code base code review

Co-authored-by: zhangjie <zhangjie@test.com>

go.mod

@@ -5,5 +5,5 @@ go 1.14
 require (
 	github.com/jackc/pgx/v4 v4.16.1
 	golang.org/x/crypto v0.0.0-20210921155107-089bfa567519 // indirect
-	gorm.io/gorm v1.23.4
+	gorm.io/gorm v1.23.6
 )

go.sum

@@ -186,4 +186,6 @@ gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gorm.io/gorm v1.23.4 h1:1BKWM67O6CflSLcwGQR7ccfmC4ebOxQrTfOQGRE9wjg=
 gorm.io/gorm v1.23.4/go.mod h1:l2lP/RyAtc1ynaTjFksBde/O8v9oOGIApu2/xRitmZk=
+gorm.io/gorm v1.23.6 h1:KFLdNgri4ExFFGTRGGFWON2P1ZN28+9SJRN8voOoYe0=
+gorm.io/gorm v1.23.6/go.mod h1:l2lP/RyAtc1ynaTjFksBde/O8v9oOGIApu2/xRitmZk=
 honnef.co/go/tools v0.0.1-2019.2.3/go.mod h1:a3bituU0lyd329TUQxRnasdCoJDkEUEAqEt0JzvZhAg=

migrator.go

@@ -13,6 +13,27 @@ import (
 	"gorm.io/gorm/schema"
 )
 
+const indexSql = `
+select
+    t.relname as table_name,
+    i.relname as index_name,
+    a.attname as column_name,
+    ix.indisunique as non_unique,
+	ix.indisprimary as primary
+from
+    pg_class t,
+    pg_class i,
+    pg_index ix,
+    pg_attribute a
+where
+    t.oid = ix.indrelid
+    and i.oid = ix.indexrelid
+    and a.attrelid = t.oid
+    and a.attnum = ANY(ix.indkey)
+    and t.relkind = 'r'
+    and t.relname = ?
+`
+
 type Migrator struct {
 	migrator.Migrator
 }
@@ -586,3 +607,53 @@ func (m Migrator) getColumnSequenceName(tx *gorm.DB, stmt *gorm.Statement, field
 	)
 	return
 }
+
+func (m Migrator) GetIndexes(value interface{}) ([]gorm.Index, error) {
+	indexes := make([]gorm.Index, 0)
+
+	err := m.RunWithValue(value, func(stmt *gorm.Statement) error {
+		result := make([]*Index, 0)
+		scanErr := m.DB.Raw(indexSql, stmt.Table).Scan(&result).Error
+		if scanErr != nil {
+			return scanErr
+		}
+		indexMap := groupByIndexName(result)
+		for _, idx := range indexMap {
+			tempIdx := &migrator.Index{
+				TableName: idx[0].TableName,
+				NameValue: idx[0].IndexName,
+				PrimaryKeyValue: sql.NullBool{
+					Bool:  idx[0].Primary,
+					Valid: true,
+				},
+				UniqueValue: sql.NullBool{
+					Bool:  idx[0].NonUnique,
+					Valid: true,
+				},
+			}
+			for _, x := range idx {
+				tempIdx.ColumnList = append(tempIdx.ColumnList, x.ColumnName)
+			}
+			indexes = append(indexes, tempIdx)
+		}
+		return nil
+	})
+	return indexes, err
+}
+
+// Index table index info
+type Index struct {
+	TableName  string `gorm:"column:table_name"`
+	ColumnName string `gorm:"column:column_name"`
+	IndexName  string `gorm:"column:index_name"`
+	NonUnique  bool   `gorm:"column:non_unique"`
+	Primary    bool   `gorm:"column:primary"`
+}
+
+func groupByIndexName(indexList []*Index) map[string][]*Index {
+	columnIndexMap := make(map[string][]*Index, len(indexList))
+	for _, idx := range indexList {
+		columnIndexMap[idx.IndexName] = append(columnIndexMap[idx.IndexName], idx)
+	}
+	return columnIndexMap
+}