private async Task <IReadOnlyCollection <IDatabaseIndex> > LoadIndexesAsyncCore(Identifier tableName, PostgreSqlTableQueryCache queryCache, CancellationToken cancellationToken)
{
var queryResult = await DbConnection.QueryAsync <IndexColumns>(
IndexesQuery,
new { SchemaName = tableName.Schema, TableName = tableName.LocalName },
cancellationToken
).ConfigureAwait(false);
if (queryResult.Empty())
{
return(Array.Empty <IDatabaseIndex>());
}
var indexColumns = queryResult.GroupBy(row => new { row.IndexName, row.IsUnique, row.IsPrimary, row.KeyColumnCount }).ToList();
if (indexColumns.Empty())
{
return(Array.Empty <IDatabaseIndex>());
}
var columns = await queryCache.GetColumnsAsync(tableName, cancellationToken).ConfigureAwait(false);
var columnLookup = GetColumnLookup(columns);
var result = new List <IDatabaseIndex>(indexColumns.Count);
foreach (var indexInfo in indexColumns)
{
var isUnique = indexInfo.Key.IsUnique;
var indexName = Identifier.CreateQualifiedIdentifier(indexInfo.Key.IndexName);
var indexCols = indexInfo
.OrderBy(row => row.IndexColumnId)
.Where(row => row.IndexColumnExpression != null)
.Select(row => new
{
row.IsDescending,
Expression = row.IndexColumnExpression,
Column = row.IndexColumnExpression != null && columnLookup.ContainsKey(row.IndexColumnExpression)
? columnLookup[row.IndexColumnExpression]
: null
})
.Select(row =>
{
var order = row.IsDescending ? IndexColumnOrder.Descending : IndexColumnOrder.Ascending;
var expression = row.Column != null
? Dialect.QuoteName(row.Column.Name)
: row.Expression !;
return(row.Column != null
? new PostgreSqlDatabaseIndexColumn(expression, row.Column, order)
: new PostgreSqlDatabaseIndexColumn(expression, order));
})
.Take(indexInfo.Key.KeyColumnCount)
.ToList();
var includedCols = indexInfo
.OrderBy(row => row.IndexColumnId)
.Skip(indexInfo.Key.KeyColumnCount)
.Where(row => row.IndexColumnExpression != null && columnLookup.ContainsKey(row.IndexColumnExpression))
.Select(row => columnLookup[row.IndexColumnExpression !])
/// <summary>
/// Retrieves indexes that relate to the given table.
/// </summary>
/// <param name="tableName">A table name.</param>
/// <param name="queryCache">A query cache for the given context.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>A collection of indexes.</returns>
/// <exception cref="ArgumentNullException"><paramref name="tableName"/> or <paramref name="queryCache"/> are <c>null</c>.</exception>
protected override Task <IReadOnlyCollection <IDatabaseIndex> > LoadIndexesAsync(Identifier tableName, PostgreSqlTableQueryCache queryCache, CancellationToken cancellationToken)
{
if (tableName == null)
{
throw new ArgumentNullException(nameof(tableName));
}
if (queryCache == null)
{
throw new ArgumentNullException(nameof(queryCache));
}
return(LoadIndexesAsyncCore(tableName, queryCache, cancellationToken));
}
