Support partial index

src/backend/index_builder.rs

@@ -29,6 +29,8 @@ pub trait IndexBuilder: QuotedBuilder {
         self.prepare_index_type(&create.index_type, sql);
 
         self.prepare_index_columns(&create.index.columns, sql);
+
+        self.prepare_filter(&create.r#where, sql);
     }
 
     /// Translate [`IndexDropStatement`] into SQL statement.
@@ -71,6 +73,10 @@ pub trait IndexBuilder: QuotedBuilder {
         write!(sql, ")").unwrap();
     }
 
+    #[doc(hidden)]
+    // Write WHERE clause for partial index. This function is not available in MySQL.
+    fn prepare_filter(&self, _condition: &ConditionHolder, _sql: &mut SqlWriter) {}
+
     #[doc(hidden)]
     /// Write index name.
     fn prepare_index_name(&self, name: &Option<String>, sql: &mut SqlWriter) {

src/backend/postgres/index.rs

@@ -32,6 +32,8 @@ impl IndexBuilder for PostgresQueryBuilder {
         self.prepare_index_type(&create.index_type, sql);
 
         self.prepare_index_columns(&create.index.columns, sql);
+
+        self.prepare_filter(&create.r#where, sql);
     }
 
     fn prepare_index_drop_statement(&self, drop: &IndexDropStatement, sql: &mut SqlWriter) {
@@ -57,6 +59,12 @@ impl IndexBuilder for PostgresQueryBuilder {
         }
     }
 
+    fn prepare_filter(&self, condition: &ConditionHolder, sql: &mut SqlWriter) {
+        let mut _params: Vec<Value> = Vec::new();
+        let mut _collector = |v| _params.push(v);
+        self.prepare_condition(condition, "WHERE", sql, &mut _collector);
+    }
+
     fn prepare_index_prefix(&self, create: &IndexCreateStatement, sql: &mut SqlWriter) {
         if create.primary {
             write!(sql, "PRIMARY KEY ").unwrap();

src/backend/sqlite/index.rs

@@ -29,6 +29,8 @@ impl IndexBuilder for SqliteQueryBuilder {
         }
 
         self.prepare_index_columns(&create.index.columns, sql);
+
+        self.prepare_filter(&create.r#where, sql);
     }
 
     fn prepare_index_drop_statement(&self, drop: &IndexDropStatement, sql: &mut SqlWriter) {
@@ -46,6 +48,12 @@ impl IndexBuilder for SqliteQueryBuilder {
 
     fn write_column_index_prefix(&self, _col_prefix: &Option<u32>, _sql: &mut SqlWriter) {}
 
+    fn prepare_filter(&self, condition: &ConditionHolder, sql: &mut SqlWriter) {
+        let mut _params: Vec<Value> = Vec::new();
+        let mut _collector = |v| _params.push(v);
+        self.prepare_condition(condition, "WHERE", sql, &mut _collector);
+    }
+
     fn prepare_index_prefix(&self, create: &IndexCreateStatement, sql: &mut SqlWriter) {
         if create.primary {
             write!(sql, "PRIMARY KEY ").unwrap();

src/index/create.rs

@@ -1,5 +1,7 @@
 use super::common::*;
+use crate::query::IntoCondition;
 use crate::{backend::SchemaBuilder, prepare::*, types::*, SchemaStatementBuilder};
+use crate::{ConditionHolder, ConditionalStatement};
 
 /// Create an index for an existing table
 ///
@@ -120,6 +122,28 @@ use crate::{backend::SchemaBuilder, prepare::*, types::*, SchemaStatementBuilder
 ///     r#"CREATE INDEX "idx-glyph-aspect" ON "glyph" ("aspect" ASC)"#
 /// );
 /// ```
+///
+/// Partial Index with prefix and order
+/// ```
+/// use sea_query::{tests_cfg::*, *};
+///
+/// let index = Index::create()
+///     .name("idx-glyph-aspect")
+///     .table(Glyph::Table)
+///     .col((Glyph::Aspect, 64, IndexOrder::Asc))
+///     .and_where(Expr::tbl(Glyph::Table, Glyph::Aspect).is_in(vec![3, 4]))
+///     .to_owned();
+///
+/// assert_eq!(
+///     index.to_string(PostgresQueryBuilder),
+///     r#"CREATE INDEX "idx-glyph-aspect" ON "glyph" ("aspect" (64) ASC) WHERE "glyph"."aspect" IN ($1, $2)"#
+/// );
+/// assert_eq!(
+///     index.to_string(SqliteQueryBuilder),
+///     r#"CREATE INDEX "idx-glyph-aspect" ON "glyph" ("aspect" ASC) WHERE "glyph"."aspect" IN (?, ?)"#
+/// );
+/// ```
+
 #[derive(Debug, Clone)]
 pub struct IndexCreateStatement {
     pub(crate) table: Option<DynIden>,
@@ -128,6 +152,7 @@ pub struct IndexCreateStatement {
     pub(crate) unique: bool,
     pub(crate) index_type: Option<IndexType>,
     pub(crate) if_not_exists: bool,
+    pub(crate) r#where: ConditionHolder,
 }
 
 /// Specification of a table index
@@ -155,6 +180,7 @@ impl IndexCreateStatement {
             unique: false,
             index_type: None,
             if_not_exists: false,
+            r#where: ConditionHolder::new(),
         }
     }
 
@@ -233,6 +259,7 @@ impl IndexCreateStatement {
             unique: self.unique,
             index_type: self.index_type.take(),
             if_not_exists: self.if_not_exists,
+            r#where: self.r#where.clone(),
         }
     }
 }
@@ -250,3 +277,18 @@ impl SchemaStatementBuilder for IndexCreateStatement {
         sql.result()
     }
 }
+
+impl ConditionalStatement for IndexCreateStatement {
+    fn and_or_where(&mut self, condition: LogicalChainOper) -> &mut Self {
+        self.r#where.add_and_or(condition);
+        self
+    }
+
+    fn cond_where<C>(&mut self, condition: C) -> &mut Self
+    where
+        C: IntoCondition,
+    {
+        self.r#where.add_condition(condition.into_condition());
+        self
+    }
+}

src/query/shim.rs

@@ -12,3 +12,4 @@ impl_ordered_statement!(delete_statement_ordered, DeleteStatement);
 impl_conditional_statement!(select_statement_conditional, SelectStatement);
 impl_conditional_statement!(update_statement_conditional, UpdateStatement);
 impl_conditional_statement!(delete_statement_conditional, DeleteStatement);
+impl_conditional_statement!(index_create_conditional, IndexCreateStatement);