db2执行计划解析问题

Scan/Fetch TBSCAN Table Scan—Retrieves rows by reading all required
data directly from the data pages.
IXSCAN Index Scan—Scans an index of a table with optional
start/stop conditions, producing an ordered stream of
rows.
FETCH Fetch From Table—Fetches columns from a table
using a specifi c record identifi er.
EISCAN Extended Index Scan—Scans a user-defi ned index to
produce a reduced stream of rows.
RIDSCN Row Identifi er Scan—Scans a list of row identifi ers
(RIDs) obtained from one or more indexes.
Joins MSJOIN Merge Scan Join—A join where both outer and inner
tables must be in join-predicate order.
NLJOIN Nested Loop Join—A join that accesses an inner
table once for each row of the outer table.
HSJOIN Hash Join—A join where two or more tables are
hashed on the join columns.收起

这些操作见名知义，
tbscan=table scan 表扫描
fetch 先索引扫描， 然后从表中取数
hsjoin是一种关联方式， 优化器在执定执行计划时自行决定采用何种方式， 常见的还有merge， nest loop收起