[Feat] Asynchronous indexing (#4480)

Co-authored-by: Micha de Vries <micha@devrie.sh>

core/src/cnf/mod.rs

@@ -31,10 +31,14 @@ pub static NORMAL_FETCH_SIZE: Lazy<u32> = lazy_env_parse!("SURREAL_NORMAL_FETCH_
 /// The maximum number of keys that should be scanned at once for export queries.
 pub static EXPORT_BATCH_SIZE: Lazy<u32> = lazy_env_parse!("SURREAL_EXPORT_BATCH_SIZE", u32, 1000);
 
-/// The maximum number of keys that should be fetched when streaming range scanns in a Scanner.
+/// The maximum number of keys that should be fetched when streaming range scans in a Scanner.
 pub static MAX_STREAM_BATCH_SIZE: Lazy<u32> =
 	lazy_env_parse!("SURREAL_MAX_STREAM_BATCH_SIZE", u32, 1000);
 
+/// The maximum number of keys that should be scanned at once per concurrent indexing batch.
+pub static INDEXING_BATCH_SIZE: Lazy<u32> =
+	lazy_env_parse!("SURREAL_INDEXING_BATCH_SIZE", u32, 250);
+
 /// Forward all signup/signin/authenticate query errors to a client performing authentication. Do not use in production.
 pub static INSECURE_FORWARD_ACCESS_ERRORS: Lazy<bool> =
 	lazy_env_parse!("SURREAL_INSECURE_FORWARD_ACCESS_ERRORS", bool, false);

core/src/ctx/context.rs

@@ -8,6 +8,8 @@ use crate::err::Error;
 use crate::idx::planner::executor::QueryExecutor;
 use crate::idx::planner::{IterationStage, QueryPlanner};
 use crate::idx::trees::store::IndexStores;
+#[cfg(not(target_arch = "wasm32"))]
+use crate::kvs::IndexBuilder;
 use crate::kvs::Transaction;
 use crate::sql::value::Value;
 use channel::Sender;
@@ -63,6 +65,9 @@ pub struct MutableContext {
 	iteration_stage: Option<IterationStage>,
 	// The index store
 	index_stores: IndexStores,
+	// The index concurrent builders
+	#[cfg(not(target_arch = "wasm32"))]
+	index_builder: Option<IndexBuilder>,
 	// Capabilities
 	capabilities: Arc<Capabilities>,
 	#[cfg(any(
@@ -110,6 +115,7 @@ impl MutableContext {
 		time_out: Option<Duration>,
 		capabilities: Capabilities,
 		index_stores: IndexStores,
+		#[cfg(not(target_arch = "wasm32"))] index_builder: IndexBuilder,
 		#[cfg(any(
 			feature = "kv-mem",
 			feature = "kv-surrealkv",
@@ -130,6 +136,8 @@ impl MutableContext {
 			iteration_stage: None,
 			capabilities: Arc::new(capabilities),
 			index_stores,
+			#[cfg(not(target_arch = "wasm32"))]
+			index_builder: Some(index_builder),
 			#[cfg(any(
 				feature = "kv-mem",
 				feature = "kv-surrealkv",
@@ -159,6 +167,8 @@ impl MutableContext {
 			iteration_stage: None,
 			capabilities: Arc::new(Capabilities::default()),
 			index_stores: IndexStores::default(),
+			#[cfg(not(target_arch = "wasm32"))]
+			index_builder: None,
 			#[cfg(any(
 				feature = "kv-mem",
 				feature = "kv-surrealkv",
@@ -184,6 +194,8 @@ impl MutableContext {
 			iteration_stage: parent.iteration_stage.clone(),
 			capabilities: parent.capabilities.clone(),
 			index_stores: parent.index_stores.clone(),
+			#[cfg(not(target_arch = "wasm32"))]
+			index_builder: parent.index_builder.clone(),
 			#[cfg(any(
 				feature = "kv-mem",
 				feature = "kv-surrealkv",
@@ -220,6 +232,8 @@ impl MutableContext {
 			iteration_stage: parent.iteration_stage.clone(),
 			capabilities: parent.capabilities.clone(),
 			index_stores: parent.index_stores.clone(),
+			#[cfg(not(target_arch = "wasm32"))]
+			index_builder: parent.index_builder.clone(),
 			#[cfg(any(
 				feature = "kv-mem",
 				feature = "kv-surrealkv",
@@ -234,6 +248,34 @@ impl MutableContext {
 		}
 	}
 
+	/// Create a new child from a frozen context.
+	pub fn new_concurrent(from: &Context) -> Self {
+		Self {
+			values: HashMap::default(),
+			deadline: None,
+			cancelled: Arc::new(AtomicBool::new(false)),
+			notifications: from.notifications.clone(),
+			query_planner: from.query_planner.clone(),
+			query_executor: from.query_executor.clone(),
+			iteration_stage: from.iteration_stage.clone(),
+			capabilities: from.capabilities.clone(),
+			index_stores: from.index_stores.clone(),
+			#[cfg(not(target_arch = "wasm32"))]
+			index_builder: from.index_builder.clone(),
+			#[cfg(any(
+				feature = "kv-mem",
+				feature = "kv-surrealkv",
+				feature = "kv-rocksdb",
+				feature = "kv-fdb",
+				feature = "kv-tikv",
+			))]
+			temporary_directory: from.temporary_directory.clone(),
+			transaction: None,
+			isolated: false,
+			parent: None,
+		}
+	}
+
 	/// Add a value to the context. It overwrites any previously set values
 	/// with the same key.
 	pub fn add_value<K>(&mut self, key: K, value: Arc<Value>)
@@ -327,6 +369,12 @@ impl MutableContext {
 		&self.index_stores
 	}
 
+	/// Get the index_builder for this context/ds
+	#[cfg(not(target_arch = "wasm32"))]
+	pub(crate) fn get_index_builder(&self) -> Option<&IndexBuilder> {
+		self.index_builder.as_ref()
+	}
+
 	/// Check if the context is done. If it returns `None` the operation may
 	/// proceed, otherwise the operation should be stopped.
 	pub fn done(&self) -> Option<Reason> {

core/src/doc/index.rs

@@ -7,6 +7,8 @@ use crate::idx::ft::FtIndex;
 use crate::idx::trees::mtree::MTreeIndex;
 use crate::idx::IndexKeyBase;
 use crate::key;
+#[cfg(not(target_arch = "wasm32"))]
+use crate::kvs::ConsumeResult;
 use crate::kvs::TransactionType;
 use crate::sql::array::Array;
 use crate::sql::index::{HnswParams, Index, MTreeParams, SearchParams};
@@ -46,13 +48,42 @@ impl Document {
 		// Loop through all index statements
 		for ix in ixs.iter() {
 			// Calculate old values
-			let o = build_opt_values(stk, ctx, opt, ix, &self.initial).await?;
+			let o = Self::build_opt_values(stk, ctx, opt, ix, &self.initial).await?;
 
 			// Calculate new values
-			let n = build_opt_values(stk, ctx, opt, ix, &self.current).await?;
+			let n = Self::build_opt_values(stk, ctx, opt, ix, &self.current).await?;
 
 			// Update the index entries
 			if targeted_force || o != n {
+				Self::one_index(stk, ctx, opt, ix, o, n, rid).await?;
+			}
+		}
+		// Carry on
+		Ok(())
+	}
+
+	async fn one_index(
+		stk: &mut Stk,
+		ctx: &Context,
+		opt: &Options,
+		ix: &DefineIndexStatement,
+		o: Option<Vec<Value>>,
+		n: Option<Vec<Value>>,
+		rid: &Thing,
+	) -> Result<(), Error> {
+		#[cfg(not(target_arch = "wasm32"))]
+		let (o, n) = if let Some(ib) = ctx.get_index_builder() {
+			match ib.consume(ix, o, n, rid).await? {
+				// The index builder consumed the value, which means it is currently building the index asynchronously,
+				// we don't index the document and let the index builder do it later.
+				ConsumeResult::Enqueued => return Ok(()),
+				// The index builder is done, the index has been built, we can proceed normally
+				ConsumeResult::Ignored(o, n) => (o, n),
+			}
+		} else {
+			(o, n)
+		};
+
 		// Store all the variable and parameters required by the index operation
 		let mut ic = IndexOperation::new(opt, ix, o, n, rid);
 
@@ -63,25 +94,21 @@ impl Document {
 			Index::Search(p) => ic.index_full_text(stk, ctx, p).await?,
 			Index::MTree(p) => ic.index_mtree(stk, ctx, p).await?,
 			Index::Hnsw(p) => ic.index_hnsw(ctx, p).await?,
-				};
 		}
-		}
-		// Carry on
 		Ok(())
 	}
-}
 
-/// Extract from the given document, the values required by the index and put then in an array.
+	/// Extract from the given document, the values required by the index and put then in an array.
-/// Eg. IF the index is composed of the columns `name` and `instrument`
+	/// Eg. IF the index is composed of the columns `name` and `instrument`
-/// Given this doc: { "id": 1, "instrument":"piano", "name":"Tobie" }
+	/// Given this doc: { "id": 1, "instrument":"piano", "name":"Tobie" }
-/// It will return: ["Tobie", "piano"]
+	/// It will return: ["Tobie", "piano"]
-async fn build_opt_values(
+	pub(crate) async fn build_opt_values(
 		stk: &mut Stk,
 		ctx: &Context,
 		opt: &Options,
 		ix: &DefineIndexStatement,
 		doc: &CursorDoc,
-) -> Result<Option<Vec<Value>>, Error> {
+	) -> Result<Option<Vec<Value>>, Error> {
 		if !doc.doc.as_ref().is_some() {
 			return Ok(None);
 		}
@@ -91,6 +118,7 @@ async fn build_opt_values(
 			o.push(v);
 		}
 		Ok(Some(o))
+	}
 }
 
 /// Extract from the given document, the values required by the index and put then in an array.

core/src/err/mod.rs

@@ -933,6 +933,12 @@ pub enum Error {
 		db: String,
 	},
 
+	/// A database index entry for the specified table is already building
+	#[error("Database index `{index}` is currently building")]
+	IndexAlreadyBuilding {
+		index: String,
+	},
+
 	/// The session has expired either because the token used
 	/// to establish it has expired or because an expiration
 	/// was explicitly defined when establishing it

core/src/idx/index.rs

@@ -0,0 +1,337 @@
+use crate::ctx::Context;
+use crate::dbs::Options;
+use crate::err::Error;
+use crate::idx::ft::FtIndex;
+use crate::idx::trees::mtree::MTreeIndex;
+use crate::idx::IndexKeyBase;
+use crate::key;
+use crate::kvs::TransactionType;
+use crate::sql::index::{HnswParams, MTreeParams, SearchParams};
+use crate::sql::statements::DefineIndexStatement;
+use crate::sql::{Array, Index, Part, Thing, Value};
+use reblessive::tree::Stk;
+
+pub(crate) struct IndexOperation<'a> {
+	ctx: &'a Context,
+	opt: &'a Options,
+	ix: &'a DefineIndexStatement,
+	/// The old values (if existing)
+	o: Option<Vec<Value>>,
+	/// The new values (if existing)
+	n: Option<Vec<Value>>,
+	rid: &'a Thing,
+}
+
+impl<'a> IndexOperation<'a> {
+	pub(crate) fn new(
+		ctx: &'a Context,
+		opt: &'a Options,
+		ix: &'a DefineIndexStatement,
+		o: Option<Vec<Value>>,
+		n: Option<Vec<Value>>,
+		rid: &'a Thing,
+	) -> Self {
+		Self {
+			ctx,
+			opt,
+			ix,
+			o,
+			n,
+			rid,
+		}
+	}
+
+	pub(crate) async fn compute(&mut self, stk: &mut Stk) -> Result<(), Error> {
+		// Index operation dispatching
+		match &self.ix.index {
+			Index::Uniq => self.index_unique().await,
+			Index::Idx => self.index_non_unique().await,
+			Index::Search(p) => self.index_full_text(stk, p).await,
+			Index::MTree(p) => self.index_mtree(stk, p).await,
+			Index::Hnsw(p) => self.index_hnsw(p).await,
+		}
+	}
+
+	fn get_unique_index_key(&self, v: &'a Array) -> Result<key::index::Index, Error> {
+		Ok(key::index::Index::new(
+			self.opt.ns()?,
+			self.opt.db()?,
+			&self.ix.what,
+			&self.ix.name,
+			v,
+			None,
+		))
+	}
+
+	fn get_non_unique_index_key(&self, v: &'a Array) -> Result<key::index::Index, Error> {
+		Ok(key::index::Index::new(
+			self.opt.ns()?,
+			self.opt.db()?,
+			&self.ix.what,
+			&self.ix.name,
+			v,
+			Some(&self.rid.id),
+		))
+	}
+
+	async fn index_unique(&mut self) -> Result<(), Error> {
+		// Lock the transaction
+		let tx = self.ctx.tx();
+		let mut txn = tx.lock().await;
+		// Delete the old index data
+		if let Some(o) = self.o.take() {
+			let i = Indexable::new(o, self.ix);
+			for o in i {
+				let key = self.get_unique_index_key(&o)?;
+				match txn.delc(key, Some(self.rid)).await {
+					Err(Error::TxConditionNotMet) => Ok(()),
+					Err(e) => Err(e),
+					Ok(v) => Ok(v),
+				}?
+			}
+		}
+		// Create the new index data
+		if let Some(n) = self.n.take() {
+			let i = Indexable::new(n, self.ix);
+			for n in i {
+				if !n.is_all_none_or_null() {
+					let key = self.get_unique_index_key(&n)?;
+					if txn.putc(key, self.rid, None).await.is_err() {
+						let key = self.get_unique_index_key(&n)?;
+						let val = txn.get(key, None).await?.unwrap();
+						let rid: Thing = val.into();
+						return self.err_index_exists(rid, n);
+					}
+				}
+			}
+		}
+		Ok(())
+	}
+
+	async fn index_non_unique(&mut self) -> Result<(), Error> {
+		// Lock the transaction
+		let tx = self.ctx.tx();
+		let mut txn = tx.lock().await;
+		// Delete the old index data
+		if let Some(o) = self.o.take() {
+			let i = Indexable::new(o, self.ix);
+			for o in i {
+				let key = self.get_non_unique_index_key(&o)?;
+				match txn.delc(key, Some(self.rid)).await {
+					Err(Error::TxConditionNotMet) => Ok(()),
+					Err(e) => Err(e),
+					Ok(v) => Ok(v),
+				}?
+			}
+		}
+		// Create the new index data
+		if let Some(n) = self.n.take() {
+			let i = Indexable::new(n, self.ix);
+			for n in i {
+				let key = self.get_non_unique_index_key(&n)?;
+				if txn.putc(key, self.rid, None).await.is_err() {
+					let key = self.get_non_unique_index_key(&n)?;
+					let val = txn.get(key, None).await?.unwrap();
+					let rid: Thing = val.into();
+					return self.err_index_exists(rid, n);
+				}
+			}
+		}
+		Ok(())
+	}
+
+	fn err_index_exists(&self, rid: Thing, n: Array) -> Result<(), Error> {
+		Err(Error::IndexExists {
+			thing: rid,
+			index: self.ix.name.to_string(),
+			value: match n.len() {
+				1 => n.first().unwrap().to_string(),
+				_ => n.to_string(),
+			},
+		})
+	}
+
+	async fn index_full_text(&mut self, stk: &mut Stk, p: &SearchParams) -> Result<(), Error> {
+		let ikb = IndexKeyBase::new(self.opt.ns()?, self.opt.db()?, self.ix)?;
+
+		let mut ft =
+			FtIndex::new(self.ctx, self.opt, &p.az, ikb, p, TransactionType::Write).await?;
+
+		if let Some(n) = self.n.take() {
+			ft.index_document(stk, self.ctx, self.opt, self.rid, n).await?;
+		} else {
+			ft.remove_document(self.ctx, self.rid).await?;
+		}
+		ft.finish(self.ctx).await
+	}
+
+	async fn index_mtree(&mut self, stk: &mut Stk, p: &MTreeParams) -> Result<(), Error> {
+		let txn = self.ctx.tx();
+		let ikb = IndexKeyBase::new(self.opt.ns()?, self.opt.db()?, self.ix)?;
+		let mut mt =
+			MTreeIndex::new(self.ctx.get_index_stores(), &txn, ikb, p, TransactionType::Write)
+				.await?;
+		// Delete the old index data
+		if let Some(o) = self.o.take() {
+			mt.remove_document(stk, &txn, self.rid, &o).await?;
+		}
+		// Create the new index data
+		if let Some(n) = self.n.take() {
+			mt.index_document(stk, &txn, self.rid, &n).await?;
+		}
+		mt.finish(&txn).await
+	}
+
+	async fn index_hnsw(&mut self, p: &HnswParams) -> Result<(), Error> {
+		let hnsw = self.ctx.get_index_stores().get_index_hnsw(self.opt, self.ix, p).await?;
+		let mut hnsw = hnsw.write().await;
+		// Delete the old index data
+		if let Some(o) = self.o.take() {
+			hnsw.remove_document(self.rid, &o)?;
+		}
+		// Create the new index data
+		if let Some(n) = self.n.take() {
+			hnsw.index_document(self.rid, &n)?;
+		}
+		Ok(())
+	}
+}
+
+/// Extract from the given document, the values required by the index and put then in an array.
+/// Eg. IF the index is composed of the columns `name` and `instrument`
+/// Given this doc: { "id": 1, "instrument":"piano", "name":"Tobie" }
+/// It will return: ["Tobie", "piano"]
+struct Indexable(Vec<(Value, bool)>);
+
+impl Indexable {
+	fn new(vals: Vec<Value>, ix: &DefineIndexStatement) -> Self {
+		let mut source = Vec::with_capacity(vals.len());
+		for (v, i) in vals.into_iter().zip(ix.cols.0.iter()) {
+			let f = matches!(i.0.last(), Some(&Part::Flatten));
+			source.push((v, f));
+		}
+		Self(source)
+	}
+}
+
+impl IntoIterator for Indexable {
+	type Item = Array;
+	type IntoIter = Combinator;
+
+	fn into_iter(self) -> Self::IntoIter {
+		Combinator::new(self.0)
+	}
+}
+
+struct Combinator {
+	iterators: Vec<Box<dyn ValuesIterator>>,
+	has_next: bool,
+}
+
+impl Combinator {
+	fn new(source: Vec<(Value, bool)>) -> Self {
+		let mut iterators: Vec<Box<dyn ValuesIterator>> = Vec::new();
+		// We create an iterator for each idiom
+		for (v, f) in source {
+			if !f {
+				// Iterator for not flattened values
+				if let Value::Array(v) = v {
+					iterators.push(Box::new(MultiValuesIterator::new(v.0)));
+					continue;
+				}
+			}
+			iterators.push(Box::new(SingleValueIterator(v)));
+		}
+		Self {
+			iterators,
+			has_next: true,
+		}
+	}
+}
+
+impl Iterator for Combinator {
+	type Item = Array;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		if !self.has_next {
+			return None;
+		}
+		let mut o = Vec::with_capacity(self.iterators.len());
+		// Create the combination and advance to the next
+		self.has_next = false;
+		for i in &mut self.iterators {
+			o.push(i.current().clone());
+			if !self.has_next {
+				// We advance only one iterator per iteration
+				if i.next() {
+					self.has_next = true;
+				}
+			}
+		}
+		let o = Array::from(o);
+		Some(o)
+	}
+}
+
+trait ValuesIterator: Send {
+	fn next(&mut self) -> bool;
+	fn current(&self) -> &Value;
+}
+
+struct MultiValuesIterator {
+	vals: Vec<Value>,
+	done: bool,
+	current: usize,
+	end: usize,
+}
+
+impl MultiValuesIterator {
+	fn new(vals: Vec<Value>) -> Self {
+		let len = vals.len();
+		if len == 0 {
+			Self {
+				vals,
+				done: true,
+				current: 0,
+				end: 0,
+			}
+		} else {
+			Self {
+				vals,
+				done: false,
+				current: 0,
+				end: len - 1,
+			}
+		}
+	}
+}
+
+impl ValuesIterator for MultiValuesIterator {
+	fn next(&mut self) -> bool {
+		if self.done {
+			return false;
+		}
+		if self.current == self.end {
+			self.done = true;
+			return false;
+		}
+		self.current += 1;
+		true
+	}
+
+	fn current(&self) -> &Value {
+		self.vals.get(self.current).unwrap_or(&Value::Null)
+	}
+}
+
+struct SingleValueIterator(Value);
+
+impl ValuesIterator for SingleValueIterator {
+	fn next(&mut self) -> bool {
+		false
+	}
+
+	fn current(&self) -> &Value {
+		&self.0
+	}
+}

core/src/idx/mod.rs

@@ -1,5 +1,6 @@
 pub mod docids;
 pub(crate) mod ft;
+pub(crate) mod index;
 pub mod planner;
 pub mod trees;
 

core/src/kvs/ds.rs

@@ -4,6 +4,7 @@ use crate::cf;
 use crate::ctx::MutableContext;
 #[cfg(feature = "jwks")]
 use crate::dbs::capabilities::NetTarget;
+use crate::dbs::node::Timestamp;
 use crate::dbs::{
 	Attach, Capabilities, Executor, Notification, Options, Response, Session, Variables,
 };
@@ -15,6 +16,8 @@ use crate::idx::trees::store::IndexStores;
 use crate::kvs::clock::SizedClock;
 #[allow(unused_imports)]
 use crate::kvs::clock::SystemClock;
+#[cfg(not(target_arch = "wasm32"))]
+use crate::kvs::index::IndexBuilder;
 use crate::kvs::{LockType, LockType::*, TransactionType, TransactionType::*};
 use crate::sql::{statements::DefineUserStatement, Base, Query, Value};
 use crate::syn;
@@ -55,8 +58,7 @@ const INITIAL_USER_ROLE: &str = "owner";
 #[allow(dead_code)]
 #[non_exhaustive]
 pub struct Datastore {
-	// The inner datastore type
+	transaction_factory: TransactionFactory,
-	inner: Inner,
 	// The unique id of this datastore, used in notifications
 	id: Uuid,
 	// Whether this datastore runs in strict mode by default
@@ -71,10 +73,11 @@ pub struct Datastore {
 	capabilities: Capabilities,
 	// Whether this datastore enables live query notifications to subscribers
 	pub(super) notification_channel: Option<(Sender<Notification>, Receiver<Notification>)>,
-	// Clock for tracking time. It is read only and accessible to all transactions. It is behind a mutex as tests may write to it.
-	pub(super) clock: Arc<SizedClock>,
 	// The index store cache
 	index_stores: IndexStores,
+	// The index asynchronous builder
+	#[cfg(not(target_arch = "wasm32"))]
+	index_builder: IndexBuilder,
 	#[cfg(feature = "jwks")]
 	// The JWKS object cache
 	jwks_cache: Arc<RwLock<JwksCache>>,
@@ -89,8 +92,80 @@ pub struct Datastore {
 	temporary_directory: Option<Arc<PathBuf>>,
 }
 
+#[derive(Clone)]
+pub(super) struct TransactionFactory {
+	// Clock for tracking time. It is read only and accessible to all transactions. It is behind a mutex as tests may write to it.
+	clock: Arc<SizedClock>,
+	// The inner datastore type
+	flavor: Arc<DatastoreFlavor>,
+}
+
+impl TransactionFactory {
+	#[allow(unreachable_code)]
+	pub async fn transaction(
+		&self,
+		write: TransactionType,
+		lock: LockType,
+	) -> Result<Transaction, Error> {
+		// Specify if the transaction is writeable
+		#[allow(unused_variables)]
+		let write = match write {
+			Read => false,
+			Write => true,
+		};
+		// Specify if the transaction is lockable
+		#[allow(unused_variables)]
+		let lock = match lock {
+			Pessimistic => true,
+			Optimistic => false,
+		};
+		// Create a new transaction on the datastore
+		#[allow(unused_variables)]
+		let inner = match self.flavor.as_ref() {
+			#[cfg(feature = "kv-mem")]
+			DatastoreFlavor::Mem(v) => {
+				let tx = v.transaction(write, lock).await?;
+				super::tr::Inner::Mem(tx)
+			}
+			#[cfg(feature = "kv-rocksdb")]
+			DatastoreFlavor::RocksDB(v) => {
+				let tx = v.transaction(write, lock).await?;
+				super::tr::Inner::RocksDB(tx)
+			}
+			#[cfg(feature = "kv-indxdb")]
+			DatastoreFlavor::IndxDB(v) => {
+				let tx = v.transaction(write, lock).await?;
+				super::tr::Inner::IndxDB(tx)
+			}
+			#[cfg(feature = "kv-tikv")]
+			DatastoreFlavor::TiKV(v) => {
+				let tx = v.transaction(write, lock).await?;
+				super::tr::Inner::TiKV(tx)
+			}
+			#[cfg(feature = "kv-fdb")]
+			DatastoreFlavor::FoundationDB(v) => {
+				let tx = v.transaction(write, lock).await?;
+				super::tr::Inner::FoundationDB(tx)
+			}
+			#[cfg(feature = "kv-surrealkv")]
+			DatastoreFlavor::SurrealKV(v) => {
+				let tx = v.transaction(write, lock).await?;
+				super::tr::Inner::SurrealKV(tx)
+			}
+			#[allow(unreachable_patterns)]
+			_ => unreachable!(),
+		};
+		Ok(Transaction::new(Transactor {
+			inner,
+			stash: super::stash::Stash::default(),
+			cf: cf::Writer::new(),
+			clock: self.clock.clone(),
+		}))
+	}
+}
+
 #[allow(clippy::large_enum_variant)]
-pub(super) enum Inner {
+pub(super) enum DatastoreFlavor {
 	#[cfg(feature = "kv-mem")]
 	Mem(super::mem::Datastore),
 	#[cfg(feature = "kv-rocksdb")]
@@ -108,19 +183,19 @@ pub(super) enum Inner {
 impl fmt::Display for Datastore {
 	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 		#![allow(unused_variables)]
-		match &self.inner {
+		match self.transaction_factory.flavor.as_ref() {
 			#[cfg(feature = "kv-mem")]
-			Inner::Mem(_) => write!(f, "memory"),
+			DatastoreFlavor::Mem(_) => write!(f, "memory"),
 			#[cfg(feature = "kv-rocksdb")]
-			Inner::RocksDB(_) => write!(f, "rocksdb"),
+			DatastoreFlavor::RocksDB(_) => write!(f, "rocksdb"),
 			#[cfg(feature = "kv-indxdb")]
-			Inner::IndxDB(_) => write!(f, "indxdb"),
+			DatastoreFlavor::IndxDB(_) => write!(f, "indxdb"),
 			#[cfg(feature = "kv-tikv")]
-			Inner::TiKV(_) => write!(f, "tikv"),
+			DatastoreFlavor::TiKV(_) => write!(f, "tikv"),
 			#[cfg(feature = "kv-fdb")]
-			Inner::FoundationDB(_) => write!(f, "fdb"),
+			DatastoreFlavor::FoundationDB(_) => write!(f, "fdb"),
 			#[cfg(feature = "kv-surrealkv")]
-			Inner::SurrealKV(_) => write!(f, "surrealkv"),
+			DatastoreFlavor::SurrealKV(_) => write!(f, "surrealkv"),
 			#[allow(unreachable_patterns)]
 			_ => unreachable!(),
 		}
@@ -175,13 +250,13 @@ impl Datastore {
 		clock: Option<Arc<SizedClock>>,
 	) -> Result<Datastore, Error> {
 		// Initiate the desired datastore
-		let (inner, clock): (Result<Inner, Error>, Arc<SizedClock>) = match path {
+		let (flavor, clock): (Result<DatastoreFlavor, Error>, Arc<SizedClock>) = match path {
 			// Initiate an in-memory datastore
 			"memory" => {
 				#[cfg(feature = "kv-mem")]
 				{
 					info!(target: TARGET, "Starting kvs store in {}", path);
-					let v = super::mem::Datastore::new().await.map(Inner::Mem);
+					let v = super::mem::Datastore::new().await.map(DatastoreFlavor::Mem);
 					let c = clock.unwrap_or_else(|| Arc::new(SizedClock::system()));
 					info!(target: TARGET, "Started kvs store in {}", path);
 					Ok((v, c))
@@ -196,7 +271,7 @@ impl Datastore {
 					info!(target: TARGET, "Starting kvs store at {}", path);
 					let s = s.trim_start_matches("file://");
 					let s = s.trim_start_matches("file:");
-					let v = super::rocksdb::Datastore::new(s).await.map(Inner::RocksDB);
+					let v = super::rocksdb::Datastore::new(s).await.map(DatastoreFlavor::RocksDB);
 					let c = clock.unwrap_or_else(|| Arc::new(SizedClock::system()));
 					info!(target: TARGET, "Started kvs store at {}", path);
 					Ok((v, c))
@@ -211,7 +286,7 @@ impl Datastore {
 					info!(target: TARGET, "Starting kvs store at {}", path);
 					let s = s.trim_start_matches("rocksdb://");
 					let s = s.trim_start_matches("rocksdb:");
-					let v = super::rocksdb::Datastore::new(s).await.map(Inner::RocksDB);
+					let v = super::rocksdb::Datastore::new(s).await.map(DatastoreFlavor::RocksDB);
 					let c = clock.unwrap_or_else(|| Arc::new(SizedClock::system()));
 					info!(target: TARGET, "Started kvs store at {}", path);
 					Ok((v, c))
@@ -226,7 +301,7 @@ impl Datastore {
 					info!(target: TARGET, "Starting kvs store at {}", path);
 					let s = s.trim_start_matches("indxdb://");
 					let s = s.trim_start_matches("indxdb:");
-					let v = super::indxdb::Datastore::new(s).await.map(Inner::IndxDB);
+					let v = super::indxdb::Datastore::new(s).await.map(DatastoreFlavor::IndxDB);
 					let c = clock.unwrap_or_else(|| Arc::new(SizedClock::system()));
 					info!(target: TARGET, "Started kvs store at {}", path);
 					Ok((v, c))
@@ -241,7 +316,7 @@ impl Datastore {
 					info!(target: TARGET, "Connecting to kvs store at {}", path);
 					let s = s.trim_start_matches("tikv://");
 					let s = s.trim_start_matches("tikv:");
-					let v = super::tikv::Datastore::new(s).await.map(Inner::TiKV);
+					let v = super::tikv::Datastore::new(s).await.map(DatastoreFlavor::TiKV);
 					let c = clock.unwrap_or_else(|| Arc::new(SizedClock::system()));
 					info!(target: TARGET, "Connected to kvs store at {}", path);
 					Ok((v, c))
@@ -256,7 +331,7 @@ impl Datastore {
 					info!(target: TARGET, "Connecting to kvs store at {}", path);
 					let s = s.trim_start_matches("fdb://");
 					let s = s.trim_start_matches("fdb:");
-					let v = super::fdb::Datastore::new(s).await.map(Inner::FoundationDB);
+					let v = super::fdb::Datastore::new(s).await.map(DatastoreFlavor::FoundationDB);
 					let c = clock.unwrap_or_else(|| Arc::new(SizedClock::system()));
 					info!(target: TARGET, "Connected to kvs store at {}", path);
 					Ok((v, c))
@@ -271,7 +346,8 @@ impl Datastore {
 					info!(target: TARGET, "Starting kvs store at {}", path);
 					let s = s.trim_start_matches("surrealkv://");
 					let s = s.trim_start_matches("surrealkv:");
-					let v = super::surrealkv::Datastore::new(s).await.map(Inner::SurrealKV);
+					let v =
+						super::surrealkv::Datastore::new(s).await.map(DatastoreFlavor::SurrealKV);
 					let c = clock.unwrap_or_else(|| Arc::new(SizedClock::system()));
 					info!(target: TARGET, "Started to kvs store at {}", path);
 					Ok((v, c))
@@ -286,10 +362,14 @@ impl Datastore {
 			}
 		}?;
 		// Set the properties on the datastore
-		inner.map(|inner| Self {
+		flavor.map(|flavor| {
-			id: Uuid::new_v4(),
+			let tf = TransactionFactory {
-			inner,
 				clock,
+				flavor: Arc::new(flavor),
+			};
+			Self {
+				id: Uuid::new_v4(),
+				transaction_factory: tf.clone(),
 				strict: false,
 				auth_enabled: false,
 				query_timeout: None,
@@ -297,6 +377,8 @@ impl Datastore {
 				notification_channel: None,
 				capabilities: Capabilities::default(),
 				index_stores: IndexStores::default(),
+				#[cfg(not(target_arch = "wasm32"))]
+				index_builder: IndexBuilder::new(tf),
 				#[cfg(feature = "jwks")]
 				jwks_cache: Arc::new(RwLock::new(JwksCache::new())),
 				#[cfg(any(
@@ -307,6 +389,7 @@ impl Datastore {
 					feature = "kv-tikv",
 				))]
 				temporary_directory: None,
+			}
 		})
 	}
 
@@ -389,6 +472,10 @@ impl Datastore {
 		&self.jwks_cache
 	}
 
+	pub(super) async fn clock_now(&self) -> Timestamp {
+		self.transaction_factory.clock.now().await
+	}
+
 	// Initialise the cluster and run bootstrap utilities
 	#[instrument(err, level = "trace", target = "surrealdb::core::kvs::ds", skip_all)]
 	pub async fn bootstrap(&self) -> Result<(), Error> {
@@ -551,60 +638,7 @@ impl Datastore {
 		write: TransactionType,
 		lock: LockType,
 	) -> Result<Transaction, Error> {
-		// Specify if the transaction is writeable
+		self.transaction_factory.transaction(write, lock).await
-		#[allow(unused_variables)]
-		let write = match write {
-			Read => false,
-			Write => true,
-		};
-		// Specify if the transaction is lockable
-		#[allow(unused_variables)]
-		let lock = match lock {
-			Pessimistic => true,
-			Optimistic => false,
-		};
-		// Create a new transaction on the datastore
-		#[allow(unused_variables)]
-		let inner = match &self.inner {
-			#[cfg(feature = "kv-mem")]
-			Inner::Mem(v) => {
-				let tx = v.transaction(write, lock).await?;
-				super::tr::Inner::Mem(tx)
-			}
-			#[cfg(feature = "kv-rocksdb")]
-			Inner::RocksDB(v) => {
-				let tx = v.transaction(write, lock).await?;
-				super::tr::Inner::RocksDB(tx)
-			}
-			#[cfg(feature = "kv-indxdb")]
-			Inner::IndxDB(v) => {
-				let tx = v.transaction(write, lock).await?;
-				super::tr::Inner::IndxDB(tx)
-			}
-			#[cfg(feature = "kv-tikv")]
-			Inner::TiKV(v) => {
-				let tx = v.transaction(write, lock).await?;
-				super::tr::Inner::TiKV(tx)
-			}
-			#[cfg(feature = "kv-fdb")]
-			Inner::FoundationDB(v) => {
-				let tx = v.transaction(write, lock).await?;
-				super::tr::Inner::FoundationDB(tx)
-			}
-			#[cfg(feature = "kv-surrealkv")]
-			Inner::SurrealKV(v) => {
-				let tx = v.transaction(write, lock).await?;
-				super::tr::Inner::SurrealKV(tx)
-			}
-			#[allow(unreachable_patterns)]
-			_ => unreachable!(),
-		};
-		Ok(Transaction::new(Transactor {
-			inner,
-			stash: super::stash::Stash::default(),
-			cf: cf::Writer::new(),
-			clock: self.clock.clone(),
-		}))
 	}
 
 	/// Parse and execute an SQL query
@@ -690,6 +724,8 @@ impl Datastore {
 			self.query_timeout,
 			self.capabilities.clone(),
 			self.index_stores.clone(),
+			#[cfg(not(target_arch = "wasm32"))]
+			self.index_builder.clone(),
 			#[cfg(any(
 				feature = "kv-mem",
 				feature = "kv-surrealkv",

core/src/kvs/index.rs

@@ -0,0 +1,294 @@
+use crate::cnf::{INDEXING_BATCH_SIZE, NORMAL_FETCH_SIZE};
+use crate::ctx::{Context, MutableContext};
+use crate::dbs::Options;
+use crate::doc::{CursorDoc, Document};
+use crate::err::Error;
+use crate::idx::index::IndexOperation;
+use crate::key::thing;
+use crate::kvs::ds::TransactionFactory;
+use crate::kvs::LockType::Optimistic;
+use crate::kvs::{Transaction, TransactionType};
+use crate::sql::statements::DefineIndexStatement;
+use crate::sql::{Id, Object, Thing, Value};
+use dashmap::mapref::entry::Entry;
+use dashmap::DashMap;
+use reblessive::TreeStack;
+use std::collections::VecDeque;
+use std::sync::Arc;
+use tokio::sync::Mutex;
+use tokio::task;
+use tokio::task::JoinHandle;
+
+#[derive(Clone)]
+pub(crate) enum BuildingStatus {
+	Started,
+	InitialIndexing(usize),
+	UpdatesIndexing(usize),
+	Error(Arc<Error>),
+	Built,
+}
+
+pub(crate) enum ConsumeResult {
+	/// The document has been enqueued to be indexed
+	Enqueued,
+	/// The index has been built, the document can be indexed normally
+	Ignored(Option<Vec<Value>>, Option<Vec<Value>>),
+}
+
+impl BuildingStatus {
+	fn is_error(&self) -> bool {
+		matches!(self, Self::Error(_))
+	}
+
+	fn is_built(&self) -> bool {
+		matches!(self, Self::Built)
+	}
+}
+
+impl From<BuildingStatus> for Value {
+	fn from(st: BuildingStatus) -> Self {
+		let mut o = Object::default();
+		let s = match st {
+			BuildingStatus::Started => "started",
+			BuildingStatus::InitialIndexing(count) => {
+				o.insert("count".to_string(), count.into());
+				"initial"
+			}
+			BuildingStatus::UpdatesIndexing(count) => {
+				o.insert("count".to_string(), count.into());
+				"updates"
+			}
+			BuildingStatus::Error(error) => {
+				o.insert("error".to_string(), error.to_string().into());
+				"error"
+			}
+			BuildingStatus::Built => "built",
+		};
+		o.insert("status".to_string(), s.into());
+		o.into()
+	}
+}
+
+type IndexBuilding = (Arc<Building>, JoinHandle<()>);
+
+#[derive(Clone)]
+pub(crate) struct IndexBuilder {
+	tf: TransactionFactory,
+	indexes: Arc<DashMap<Arc<DefineIndexStatement>, IndexBuilding>>,
+}
+
+impl IndexBuilder {
+	pub(super) fn new(tf: TransactionFactory) -> Self {
+		Self {
+			tf,
+			indexes: Default::default(),
+		}
+	}
+
+	pub(crate) fn build(
+		&self,
+		ctx: &Context,
+		opt: Options,
+		ix: Arc<DefineIndexStatement>,
+	) -> Result<(), Error> {
+		match self.indexes.entry(ix) {
+			Entry::Occupied(e) => {
+				// If the building is currently running we return error
+				if !e.get().1.is_finished() {
+					return Err(Error::IndexAlreadyBuilding {
+						index: e.key().name.to_string(),
+					});
+				}
+			}
+			Entry::Vacant(e) => {
+				// No index is currently building, we can start building it
+				let building = Arc::new(Building::new(ctx, self.tf.clone(), opt, e.key().clone())?);
+				let b = building.clone();
+				let jh = task::spawn(async move {
+					if let Err(err) = b.compute().await {
+						b.set_status(BuildingStatus::Error(err.into())).await;
+					}
+				});
+				e.insert((building, jh));
+			}
+		}
+		Ok(())
+	}
+
+	pub(crate) async fn consume(
+		&self,
+		ix: &DefineIndexStatement,
+		old_values: Option<Vec<Value>>,
+		new_values: Option<Vec<Value>>,
+		rid: &Thing,
+	) -> Result<ConsumeResult, Error> {
+		if let Some(r) = self.indexes.get(ix) {
+			let (b, _) = r.value();
+			return Ok(b.maybe_consume(old_values, new_values, rid).await);
+		}
+		Ok(ConsumeResult::Ignored(old_values, new_values))
+	}
+
+	pub(crate) async fn get_status(&self, ix: &DefineIndexStatement) -> Option<BuildingStatus> {
+		if let Some(a) = self.indexes.get(ix) {
+			Some(a.value().0.status.lock().await.clone())
+		} else {
+			None
+		}
+	}
+}
+
+struct Appending {
+	old_values: Option<Vec<Value>>,
+	new_values: Option<Vec<Value>>,
+	id: Id,
+}
+
+struct Building {
+	ctx: Context,
+	opt: Options,
+	tf: TransactionFactory,
+	ix: Arc<DefineIndexStatement>,
+	tb: String,
+	status: Arc<Mutex<BuildingStatus>>,
+	// Should be stored on a temporary table
+	appended: Arc<Mutex<VecDeque<Appending>>>,
+}
+
+impl Building {
+	fn new(
+		ctx: &Context,
+		tf: TransactionFactory,
+		opt: Options,
+		ix: Arc<DefineIndexStatement>,
+	) -> Result<Self, Error> {
+		Ok(Self {
+			ctx: MutableContext::new_concurrent(ctx).freeze(),
+			opt,
+			tf,
+			tb: ix.what.to_string(),
+			ix,
+			status: Arc::new(Mutex::new(BuildingStatus::Started)),
+			appended: Default::default(),
+		})
+	}
+
+	async fn set_status(&self, status: BuildingStatus) {
+		let mut s = self.status.lock().await;
+		// We want to keep only the first error
+		if !s.is_error() {
+			*s = status;
+		}
+	}
+
+	async fn maybe_consume(
+		&self,
+		old_values: Option<Vec<Value>>,
+		new_values: Option<Vec<Value>>,
+		rid: &Thing,
+	) -> ConsumeResult {
+		let mut a = self.appended.lock().await;
+		// Now that the queue is locked, we have the possibility to assess if the asynchronous build is done.
+		if a.is_empty() {
+			// If the appending queue is empty and the index is built...
+			if self.status.lock().await.is_built() {
+				// ... we return the values back, so the document can be updated the usual way
+				return ConsumeResult::Ignored(old_values, new_values);
+			}
+		}
+		a.push_back(Appending {
+			old_values,
+			new_values,
+			id: rid.id.clone(),
+		});
+		ConsumeResult::Enqueued
+	}
+
+	async fn new_read_tx(&self) -> Result<Transaction, Error> {
+		self.tf.transaction(TransactionType::Read, Optimistic).await
+	}
+
+	async fn new_write_tx_ctx(&self) -> Result<Context, Error> {
+		let tx = self.tf.transaction(TransactionType::Write, Optimistic).await?.into();
+		let mut ctx = MutableContext::new(&self.ctx);
+		ctx.set_transaction(tx);
+		Ok(ctx.freeze())
+	}
+
+	async fn compute(&self) -> Result<(), Error> {
+		let mut stack = TreeStack::new();
+
+		self.set_status(BuildingStatus::InitialIndexing(0)).await;
+		// First iteration, we index every keys
+		let ns = self.opt.ns()?;
+		let db = self.opt.db()?;
+		let beg = thing::prefix(ns, db, &self.tb);
+		let end = thing::suffix(ns, db, &self.tb);
+		let mut next = Some(beg..end);
+		let mut count = 0;
+		while let Some(rng) = next {
+			// Get the next batch of records
+			let batch = self.new_read_tx().await?.batch(rng, *INDEXING_BATCH_SIZE, true).await?;
+			// Set the next scan range
+			next = batch.next;
+			// Check there are records
+			if batch.values.is_empty() {
+				break;
+			}
+			// Create a new context with a write transaction
+			let ctx = self.new_write_tx_ctx().await?;
+			// Index the records
+			for (k, v) in batch.values.into_iter() {
+				let key: thing::Thing = (&k).into();
+				// Parse the value
+				let val: Value = (&v).into();
+				let rid: Arc<Thing> = Thing::from((key.tb, key.id)).into();
+				let doc = CursorDoc::new(Some(rid.clone()), None, val);
+				let opt_values = stack
+					.enter(|stk| Document::build_opt_values(stk, &ctx, &self.opt, &self.ix, &doc))
+					.finish()
+					.await?;
+				// Index the record
+				let mut io = IndexOperation::new(&ctx, &self.opt, &self.ix, None, opt_values, &rid);
+				stack.enter(|stk| io.compute(stk)).finish().await?;
+				count += 1;
+				self.set_status(BuildingStatus::InitialIndexing(count)).await;
+			}
+			ctx.tx().commit().await?;
+		}
+		// Second iteration, we index/remove any records that has been added or removed since the initial indexing
+		self.set_status(BuildingStatus::UpdatesIndexing(0)).await;
+		loop {
+			let mut batch = self.appended.lock().await;
+			if batch.is_empty() {
+				// If the batch is empty, we are done.
+				// Due to the lock on self.appended, we know that no external process can add an item to the queue.
+				self.set_status(BuildingStatus::Built).await;
+				// This is here to be sure the lock on back is not released early
+				batch.clear();
+				break;
+			}
+			let fetch = (*NORMAL_FETCH_SIZE as usize).min(batch.len());
+			let drain = batch.drain(0..fetch);
+			// Create a new context with a write transaction
+			let ctx = self.new_write_tx_ctx().await?;
+
+			for a in drain {
+				let rid = Thing::from((self.tb.clone(), a.id));
+				let mut io = IndexOperation::new(
+					&ctx,
+					&self.opt,
+					&self.ix,
+					a.old_values,
+					a.new_values,
+					&rid,
+				);
+				stack.enter(|stk| io.compute(stk)).finish().await?;
+				count += 1;
+				self.set_status(BuildingStatus::UpdatesIndexing(count)).await;
+			}
+			ctx.tx().commit().await?;
+		}
+		Ok(())
+	}
+}

core/src/kvs/mod.rs

@@ -33,10 +33,14 @@ mod rocksdb;
 mod surrealkv;
 mod tikv;
 
+#[cfg(not(target_arch = "wasm32"))]
+mod index;
 #[cfg(test)]
 mod tests;
 
 pub use self::ds::*;
+#[cfg(not(target_arch = "wasm32"))]
+pub(crate) use self::index::*;
 pub use self::kv::*;
 pub use self::live::*;
 pub use self::tr::*;

core/src/kvs/node.rs

@@ -25,7 +25,7 @@ impl Datastore {
 		// Open transaction and set node data
 		let txn = self.transaction(Write, Optimistic).await?;
 		let key = crate::key::root::nd::Nd::new(id);
-		let now = self.clock.now().await;
+		let now = self.clock_now().await;
 		let val = Node::new(id, now, false);
 		match run!(txn, txn.put(key, val)) {
 			Err(Error::TxKeyAlreadyExists) => Err(Error::ClAlreadyExists {
@@ -49,7 +49,7 @@ impl Datastore {
 		// Open transaction and set node data
 		let txn = self.transaction(Write, Optimistic).await?;
 		let key = crate::key::root::nd::new(id);
-		let now = self.clock.now().await;
+		let now = self.clock_now().await;
 		let val = Node::new(id, now, false);
 		run!(txn, txn.set(key, val))
 	}
@@ -86,7 +86,7 @@ impl Datastore {
 		trace!(target: TARGET, "Archiving expired nodes in the cluster");
 		// Open transaction and fetch nodes
 		let txn = self.transaction(Write, Optimistic).await?;
-		let now = self.clock.now().await;
+		let now = self.clock_now().await;
 		let nds = catch!(txn, txn.all_nodes());
 		for nd in nds.iter() {
 			// Check that the node is active

core/src/sql/statements/define/index.rs

@@ -13,7 +13,7 @@ use serde::{Deserialize, Serialize};
 use std::fmt::{self, Display};
 use std::sync::Arc;
 
-#[revisioned(revision = 3)]
+#[revisioned(revision = 4)]
 #[derive(Clone, Debug, Default, Eq, PartialEq, PartialOrd, Serialize, Deserialize, Store, Hash)]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 #[non_exhaustive]
@@ -27,6 +27,8 @@ pub struct DefineIndexStatement {
 	pub if_not_exists: bool,
 	#[revision(start = 3)]
 	pub overwrite: bool,
+	#[revision(start = 4)]
+	pub concurrently: bool,
 }
 
 impl DefineIndexStatement {
@@ -89,6 +91,25 @@ impl DefineIndexStatement {
 		.await?;
 		// Clear the cache
 		txn.clear();
+		#[cfg(not(target_arch = "wasm32"))]
+		if self.concurrently {
+			self.async_index(ctx, opt)?;
+		} else {
+			self.sync_index(stk, ctx, opt, doc).await?;
+		}
+		#[cfg(target_arch = "wasm32")]
+		self.sync_index(stk, ctx, opt, doc).await?;
+		// Ok all good
+		Ok(Value::None)
+	}
+
+	async fn sync_index(
+		&self,
+		stk: &mut Stk,
+		ctx: &Context,
+		opt: &Options,
+		doc: Option<&CursorDoc>,
+	) -> Result<(), Error> {
 		// Force queries to run
 		let opt = &opt.new_with_force(Force::Index(Arc::new([self.clone()])));
 		// Update the index data
@@ -98,8 +119,16 @@ impl DefineIndexStatement {
 			..UpdateStatement::default()
 		};
 		stm.compute(stk, ctx, opt, doc).await?;
-		// Ok all good
+		Ok(())
-		Ok(Value::None)
+	}
+
+	#[cfg(not(target_arch = "wasm32"))]
+	fn async_index(&self, ctx: &Context, opt: &Options) -> Result<(), Error> {
+		ctx.get_index_builder().ok_or(Error::Unreachable("No Index Builder"))?.build(
+			ctx,
+			opt.clone(),
+			self.clone().into(),
+		)
 	}
 }
 
@@ -119,6 +148,9 @@ impl Display for DefineIndexStatement {
 		if let Some(ref v) = self.comment {
 			write!(f, " COMMENT {v}")?
 		}
+		if self.concurrently {
+			write!(f, " CONCURRENTLY")?
+		}
 		Ok(())
 	}
 }

core/src/sql/statements/info.rs

@@ -9,9 +9,10 @@ use derive::Store;
 use revision::revisioned;
 use serde::{Deserialize, Serialize};
 use std::fmt;
+use std::ops::Deref;
 use std::sync::Arc;
 
-#[revisioned(revision = 2)]
+#[revisioned(revision = 3)]
 #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Serialize, Deserialize, Store, Hash)]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 #[non_exhaustive]
@@ -36,6 +37,8 @@ pub enum InfoStatement {
 	User(Ident, Option<Base>),
 	#[revision(start = 2)]
 	User(Ident, Option<Base>, bool),
+	#[revision(start = 3)]
+	Index(Ident, Ident, bool),
 }
 
 impl InfoStatement {
@@ -304,6 +307,23 @@ impl InfoStatement {
 					false => Value::from(res.to_string()),
 				})
 			}
+			InfoStatement::Index(index, table, _structured) => {
+				// Allowed to run?
+				opt.is_allowed(Action::View, ResourceKind::Actor, &Base::Db)?;
+				// Get the transaction
+				let txn = ctx.tx();
+				// Obtain the index
+				let res = txn.get_tb_index(opt.ns()?, opt.db()?, table, index).await?;
+				// Output
+				let mut out = Object::default();
+				#[cfg(not(target_arch = "wasm32"))]
+				if let Some(ib) = ctx.get_index_builder() {
+					if let Some(status) = ib.get_status(res.deref()).await {
+						out.insert("building".to_string(), status.into());
+					}
+				}
+				Ok(out.into())
+			}
 		}
 	}
 }
@@ -327,6 +347,8 @@ impl fmt::Display for InfoStatement {
 				Some(ref b) => write!(f, "INFO FOR USER {u} ON {b} STRUCTURE"),
 				None => write!(f, "INFO FOR USER {u} STRUCTURE"),
 			},
+			Self::Index(ref i, ref t, false) => write!(f, "INFO FOR INDEX {i} ON {t}"),
+			Self::Index(ref i, ref t, true) => write!(f, "INFO FOR INDEX {i} ON {t} STRUCTURE"),
 		}
 	}
 }
@@ -343,6 +365,7 @@ impl InfoStatement {
 			InfoStatement::Db(_) => InfoStatement::Db(true),
 			InfoStatement::Tb(t, _) => InfoStatement::Tb(t, true),
 			InfoStatement::User(u, b, _) => InfoStatement::User(u, b, true),
+			InfoStatement::Index(i, t, _) => InfoStatement::Index(i, t, true),
 		}
 	}
 }

core/src/syn/lexer/keywords.rs

@@ -85,6 +85,7 @@ pub(crate) static KEYWORDS: phf::Map<UniCase<&'static str>, TokenKind> = phf_map
 	UniCase::ascii("CLASS") => TokenKind::Keyword(Keyword::Class),
 	UniCase::ascii("COMMENT") => TokenKind::Keyword(Keyword::Comment),
 	UniCase::ascii("COMMIT") => TokenKind::Keyword(Keyword::Commit),
+	UniCase::ascii("CONCURRENTLY") => TokenKind::Keyword(Keyword::Concurrently),
 	UniCase::ascii("CONTENT") => TokenKind::Keyword(Keyword::Content),
 	UniCase::ascii("CONTINUE") => TokenKind::Keyword(Keyword::Continue),
 	UniCase::ascii("CREATE") => TokenKind::Keyword(Keyword::Create),

core/src/syn/parser/stmt/define.rs

@@ -1070,6 +1070,10 @@ impl Parser<'_> {
 						keep_pruned_connections,
 					));
 				}
+				t!("CONCURRENTLY") => {
+					self.pop_peek();
+					res.concurrently = true;
+				}
 				t!("COMMENT") => {
 					self.pop_peek();
 					res.comment = Some(self.next_token_value()?);

core/src/syn/parser/stmt/mod.rs

@@ -531,6 +531,13 @@ impl Parser<'_> {
 				let base = self.eat(t!("ON")).then(|| self.parse_base(false)).transpose()?;
 				InfoStatement::User(ident, base, false)
 			}
+			t!("INDEX") => {
+				let index = self.next_token_value()?;
+				expected!(self, t!("ON"));
+				self.eat(t!("TABLE"));
+				let table = self.next_token_value()?;
+				InfoStatement::Index(index, table, false)
+			}
 			x => unexpected!(self, x, "an info target"),
 		};
 

core/src/syn/parser/test/stmt.rs

@@ -1519,6 +1519,7 @@ fn parse_define_index() {
 			comment: None,
 			if_not_exists: false,
 			overwrite: false,
+			concurrently: false
 		}))
 	);
 
@@ -1535,6 +1536,7 @@ fn parse_define_index() {
 			comment: None,
 			if_not_exists: false,
 			overwrite: false,
+			concurrently: false
 		}))
 	);
 
@@ -1560,6 +1562,7 @@ fn parse_define_index() {
 			comment: None,
 			if_not_exists: false,
 			overwrite: false,
+			concurrently: false
 		}))
 	);
 
@@ -1586,6 +1589,7 @@ fn parse_define_index() {
 			comment: None,
 			if_not_exists: false,
 			overwrite: false,
+			concurrently: false
 		}))
 	);
 }

core/src/syn/parser/test/streaming.rs

@@ -343,6 +343,7 @@ fn statements() -> Vec<Statement> {
 			comment: None,
 			if_not_exists: false,
 			overwrite: false,
+			concurrently: false,
 		})),
 		Statement::Define(DefineStatement::Index(DefineIndexStatement {
 			name: Ident("index".to_owned()),
@@ -352,6 +353,7 @@ fn statements() -> Vec<Statement> {
 			comment: None,
 			if_not_exists: false,
 			overwrite: false,
+			concurrently: false,
 		})),
 		Statement::Define(DefineStatement::Index(DefineIndexStatement {
 			name: Ident("index".to_owned()),
@@ -370,6 +372,7 @@ fn statements() -> Vec<Statement> {
 			comment: None,
 			if_not_exists: false,
 			overwrite: false,
+			concurrently: false,
 		})),
 		Statement::Define(DefineStatement::Analyzer(DefineAnalyzerStatement {
 			name: Ident("ana".to_owned()),

core/src/syn/token/keyword.rs

@@ -52,6 +52,7 @@ keyword! {
 	Class => "CLASS",
 	Comment => "COMMENT",
 	Commit => "COMMIT",
+	Concurrently => "CONCURRENTLY",
 	Content => "CONTENT",
 	Continue => "CONTINUE",
 	Create => "CREATE",

lib/tests/define.rs

@@ -685,6 +685,38 @@ async fn define_statement_index_single() -> Result<(), Error> {
 	Ok(())
 }
 
+#[tokio::test]
+async fn define_statement_index_concurrently() -> Result<(), Error> {
+	let sql = "
+		CREATE user:1 SET email = 'test@surrealdb.com';
+		CREATE user:2 SET email = 'test@surrealdb.com';
+		DEFINE INDEX test ON user FIELDS email CONCURRENTLY;
+		SLEEP 1s;
+		INFO FOR TABLE user;
+		INFO FOR INDEX test ON user;
+	";
+	let mut t = Test::new(sql).await?;
+	t.skip_ok(4)?;
+	t.expect_val(
+		"{
+			events: {},
+			fields: {},
+			tables: {},
+			indexes: {
+				test: 'DEFINE INDEX test ON user FIELDS email CONCURRENTLY',
+			},
+			lives: {},
+		}",
+	)?;
+	t.expect_val(
+		"{
+			building: { status: 'built' }
+		}",
+	)?;
+
+	Ok(())
+}
+
 #[tokio::test]
 async fn define_statement_index_multiple() -> Result<(), Error> {
 	let sql = "