|1| SIMPLE |testa| const |PRIMARY,idx_name| PRIMARY |4| const |1| NULL |+---+---+---+---+---+---+---+---+---+---+1rowinset# 下面虽然name有索引,但是查询的列cusno没有索引,这时mysql计划possible_keys有索引,但实际key未走索引,若果cusno换成有索引的列,参照下面。mysql> expl...
Seq Scan is returned in the execution plan of the query statement. EXPLAIN SELECT * FROM public.holo_lineitem_100g; The following figure shows the returned result. Query data from a partitioned table If you query data from a partitioned table, the Seq Scan on Partitioned Table keywords ...
by hash(Orange box)The router, which is a component that takes one stream of input rows and sends them to a node according to a routing algorithm. For example, a hash router hashes columns of a row and sends the results to the node that is aggregating the result rows.Both ...
As we can see from this example the iterator structure from the actual execution plan shown in the TREE format is not reflected in the old JSON format. The filter iterator is more of a footnote in the table scan on the orders table, and all the information about rows and cost of the j...
└── • scan nodes: n1 regions: us-east1 actual row count: 15 KV time: 2ms KV contention time: 0µs KV rows decoded: 15 KV bytes read: 2.4 KiB KV gRPC calls: 1 estimated max memory allocated: 20 KiB sql cpu time: 40µs ...
Most products carry a simple barcode known as the UPC (universal product code)—a line of vertical stripes with a set of numbers printed underneath it (so someone can manually key in the product number if the barcode is misprinted or damaged in the store and won't scan through the barcode...
(Block Nested Loop) indicates use of the Block Nested-Loop algorithm, (Batched Key Access) indicates use of the Batched Key Access algorithm, and (hash join) indicates use of a hash join. That is, the keys from the table on the preceding line of the EXPLAIN output are buffered, and ...
It then scans the larger table, and performs the same hashing algorithm on the join column(s). It then probes the previously built hash table for each value and if they match, it returns a row. Nested Loops joins - Nested loops joins are useful when small subsets of data are being ...
ASTC Texture Support:ASTC stands for Adaptive Scalable Texture Compression, a lossy block-based texture compression algorithm. Surely, there are also some iOS 12 Safari Experimental Features, and we don’t have the answer to them yet. And they are Prompt For Storage Acess API Request, Enable MD...
Sort Selected rows were sorted using a sort algorithm. Union Merge The results of multiple subselects were merged or combined into a single result. Subquery Merge The results of multiple subselects were merged or combined into a single result. Bitmap Merge Multiple bitmaps were merged or combined...