LEFT JOIN sys.databases databases ON databases.database_id = stats.database_id LEFT JOIN sys.indexes indexes ON indexes.index_id = stats.index_id AND stats.object_id = indexes.object_id LEFT JOIN sys.dm_db_partition_stats partition_stats ON stats.object_id = partition_stats.object_id AND...
MySQL :: MySQL 8.0 Reference Manual :: 8.2.1.23 Avoiding Full Table Scans https://dev.mysql.com/doc/refman/8.0/en/table-scan-avoidance.html explain 语句 The output fromEXPLAINshowsALLin thetypecolumn when MySQL uses afull table scanto resolve a query. 慢SQL 分析与优化 https://mp.weixin.q...
PAD_INDEX = { ON | OFF } 指定索引填充。 默认值为 OFF。 ON 填充因子指定的可用空间百分比应用于索引的中间级别页。 如果未同时指定 FILLFACTORPAD_INDEX 设置为 ON,则使用 sys.indexes 中的填充因子值。 OFF 考虑到中间级页上的键集,将中间级页填充到接近其容量的程度,以留出足够的空间,使之至少能够容纳...
DataTable dt = DbHelperSQL.GetDataTable(connString, sql, param); return dt; } public static DataTable GetIndexs(string connString, string database, string tableName) { #region SQL string sql = string.Format(@"with IndexCTE as ( select indexes.object_id, indexes.index_id, IndexName, in...
The SQL query below shows a list of tables sorted by the largest tables first. For each table, the indexes in the table are shown. For each index it shows when the index was last used. The query is designed to collect various pieces of information in one place, and give ...
"table_scan":{ "rows":7, "cost":4.5 }, "potential_range_indexes":[ {
Columnstore indexes skip reading in columns that aren't referenced by the query. 數據行刪除可進一步減少查詢執行的 I/O,因此可改善查詢效能。 Column elimination is possible because the data is organized and compressed column by column. 相反地,當數據逐列儲存時,每個數據列中的數據行值...
Query below lists table (and view) indexes. Query selectschema_name(t.schema_id) +'.'+ t.[name]astable_view,casewhent.[type] ='U'then'Table'whent.[type] ='V'then'View'endas[object_type], i.index_id,casewheni.is_primary_key =1then'Primary key'wheni.is_unique =1then'Unique'...
This query hint virtually disallows direct use of indexed views and indexes on indexed views in the query plan. Note The indexed view remains condensed if there's a direct reference to the view in the query's SELECT part. The view also remains condensed if you specify WITH (NOEX...
sys.indexes i where database_id = @dbid and objectproperty(s.object_id,'IsUserTable') = 1 and i.object_id = s.object_id and i.index_id = s.index_id order by (user_seeks + user_scans + user_lookups + user_updates) asc