/// <summary>
/// Create a new index (or do nothing if already exists) to a collection/field
/// </summary>
public bool EnsureIndex(string collection, string name, BsonExpression expression, bool unique)
{
if (collection.IsNullOrWhiteSpace())
{
throw new ArgumentNullException(nameof(collection));
}
if (name.IsNullOrWhiteSpace())
{
throw new ArgumentNullException(nameof(name));
}
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
if (expression.IsIndexable == false)
{
throw new ArgumentException("Index expressions must contains at least one document field. Used methods must be immutable. Parameters are not supported.", nameof(expression));
}
if (name.Length > INDEX_NAME_MAX_LENGTH)
{
throw LiteException.InvalidIndexName(name, collection, "MaxLength = " + INDEX_NAME_MAX_LENGTH);
}
if (!name.IsWord())
{
throw LiteException.InvalidIndexName(name, collection, "Use only [a-Z$_]");
}
if (name.StartsWith("$"))
{
throw LiteException.InvalidIndexName(name, collection, "Index name can't starts with `$`");
}
if (name == "_id")
{
return(false); // always exists
}
return(this.AutoTransaction(transaction =>
{
var snapshot = transaction.CreateSnapshot(LockMode.Write, collection, true);
var collectionPage = snapshot.CollectionPage;
var indexer = new IndexService(snapshot, _header.Pragmas.Collation);
var data = new DataService(snapshot);
// check if index already exists
var current = collectionPage.GetCollectionIndex(name);
// if already exists, just exit
if (current != null)
{
// but if expression are different, throw error
if (current.Expression != expression.Source)
{
throw LiteException.IndexAlreadyExist(name);
}
return false;
}
LOG($"create index `{collection}.{name}`", "COMMAND");
// create index head
var index = indexer.CreateIndex(name, expression.Source, unique);
var count = 0u;
// read all objects (read from PK index)
foreach (var pkNode in new IndexAll("_id", LiteDB.Query.Ascending).Run(collectionPage, indexer))
{
using (var reader = new BufferReader(data.Read(pkNode.DataBlock)))
{
var doc = reader.ReadDocument(expression.Fields);
// first/last node in this document that will be added
IndexNode last = null;
IndexNode first = null;
// get values from expression in document
var keys = expression.Execute(doc, _header.Pragmas.Collation);
// adding index node for each value
foreach (var key in keys)
{
// when index key is an array, get items inside array.
// valid only for first level (if this items are another array, this arrays will be indexed as array)
if (key.IsArray)
{
var arr = key.AsArray;
foreach (var itemKey in arr)
{
// insert new index node
var node = indexer.AddNode(index, itemKey, pkNode.DataBlock, last);
if (first == null)
{
first = node;
}
last = node;
count++;
}
}
else
{
// insert new index node
var node = indexer.AddNode(index, key, pkNode.DataBlock, last);
if (first == null)
{
first = node;
}
last = node;
count++;
}
}
// fix single linked-list in pkNode
if (first != null)
{
last.SetNextNode(pkNode.NextNode);
pkNode.SetNextNode(first.Position);
}
}
transaction.Safepoint();
}
return true;
}));
}
/// <summary>
/// INCLUDE: Do include in result document according path expression - Works only with DocumentLookup
/// </summary>
protected IEnumerable <BsonDocument> Include(IEnumerable <BsonDocument> source, BsonExpression path)
{
// cached services
string last = null;
Snapshot snapshot = null;
IndexService indexer = null;
DataService data = null;
CollectionIndex index = null;
IDocumentLookup lookup = null;
foreach (var doc in source)
{
foreach (var value in path.Execute(doc, _pragmas.Collation)
.Where(x => x.IsDocument || x.IsArray)
.ToList())
{
// if value is document, convert this ref document into full document (do another query)
if (value.IsDocument)
{
DoInclude(value.AsDocument);
}
else
{
// if value is array, do same per item
foreach (var item in value.AsArray
.Where(x => x.IsDocument)
.Select(x => x.AsDocument))
{
DoInclude(item);
}
}
}
yield return(doc);
}
void DoInclude(BsonDocument value)
{
// works only if is a document
var refId = value["$id"];
var refCol = value["$ref"];
// if has no reference, just go out
if (refId.IsNull || !refCol.IsString)
{
return;
}
// do some cache re-using when is same $ref (almost always is the same $ref collection)
if (last != refCol.AsString)
{
last = refCol.AsString;
// initialize services
snapshot = _transaction.CreateSnapshot(LockMode.Read, last, false);
indexer = new IndexService(snapshot, _pragmas.Collation);
data = new DataService(snapshot);
lookup = new DatafileLookup(data, _pragmas.UtcDate, null);
index = snapshot.CollectionPage?.PK;
}
// fill only if index and ref node exists
if (index != null)
{
var node = indexer.Find(index, refId, false, Query.Ascending);
if (node != null)
{
// load document based on dataBlock position
var refDoc = lookup.Load(node);
value.Remove("$id");
value.Remove("$ref");
refDoc.CopyTo(value);
}
else
{
// set in ref document that was not found
value.Add("$missing", true);
}
}
}
}
/// <summary>
/// Implement internal update document
/// </summary>
private bool UpdateDocument(Snapshot snapshot, CollectionPage col, BsonDocument doc, IndexService indexer, DataService data)
{
// normalize id before find
var id = doc["_id"];
// validate id for null, min/max values
if (id.IsNull || id.IsMinValue || id.IsMaxValue)
{
throw LiteException.InvalidDataType("_id", id);
}
// find indexNode from pk index
var pkNode = indexer.Find(col.PK, id, false, LiteDB.Query.Ascending);
// if not found document, no updates
if (pkNode == null)
{
return(false);
}
// update data storage
data.Update(col, pkNode.DataBlock, doc);
// get all current non-pk index nodes from this data block (slot, key, nodePosition)
var oldKeys = indexer.GetNodeList(pkNode.NextNode)
.Select(x => new Tuple <byte, BsonValue, PageAddress>(x.Slot, x.Key, x.Position))
.ToArray();
// build a list of all new key index keys
var newKeys = new List <Tuple <byte, BsonValue, string> >();
foreach (var index in col.GetCollectionIndexes().Where(x => x.Name != "_id"))
{
// getting all keys from expression over document
var keys = index.BsonExpr.Execute(doc, _header.Pragmas.Collation);
foreach (var key in keys)
{
newKeys.Add(new Tuple <byte, BsonValue, string>(index.Slot, key, index.Name));
}
}
if (oldKeys.Length == 0 && newKeys.Count == 0)
{
return(true);
}
// get a list of all nodes that are in oldKeys but not in newKeys (must delete)
var toDelete = new HashSet <PageAddress>(oldKeys
.Where(x => newKeys.Any(n => n.Item1 == x.Item1 && n.Item2 == x.Item2) == false)
.Select(x => x.Item3));
// get a list of all keys that are not in oldKeys (must insert)
var toInsert = newKeys
.Where(x => oldKeys.Any(o => o.Item1 == x.Item1 && o.Item2 == x.Item2) == false)
.ToArray();
// if nothing to change, just exit
if (toDelete.Count == 0 && toInsert.Length == 0)
{
return(true);
}
// delete nodes and return last keeped node in list
var last = indexer.DeleteList(pkNode.Position, toDelete);
// now, insert all new nodes
foreach (var elem in toInsert)
{
var index = col.GetCollectionIndex(elem.Item3);
last = indexer.AddNode(index, elem.Item2, pkNode.DataBlock, last);
}
return(true);
}
