數(shù)據(jù)庫(kù)隔離級(jí)別(編輯修改稿)
2024-08-15 17:50 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 ead Unmited ? 2 Phase Write Lock on Row。 No Read Lock ? NonDirty Write Case: ? wlock1[x] w1[x=10] wlock2[x][blocked] w2[x=20] w2[y=20] mit2 w1[y=10] mit1 ? Read Unmited Case: ? Begin[x=50] wlock1[x] w1[x=10] NoRLock2[x] r2[x=10] abort1 ? Begin[x=50,y=50] r1[x=50] wlock1[x] w1[x=10] NoRLock2[x] r2[x=10]r2[y=50] r1[y=50] w1[y=90] mit1 11 Lock Based Isolation ? Locking Read mited ? 2 Phase Write Lock on Row。 Short duration Read Lock on Row ? Read Commited Case: ? Begin[x=50] wlock1[x] w1[x=10] RLock2[x][blocked] r2[x=10] abort1 ? Begin[x=50,y=50] r1[x=50] wlock1[x] w1[x=10] RLock2[x][blocked] r2[x=10]r2[y=50] r1[y=50] w1[y=90] mit1 ? Nonrepeatable Read Case: ? Begin[x=50] RLock1[x] r1[x=50] unlock1[x] wlock2[x][nonblocked] w2[x=10] mit2 r1[x=10] mit1 ? Begin[x=50,y=50] RLock1[x] r1[x=50] unlock1[x] r2[x=50] wlock2[x] [nonblocked] w2[x=10] r2[y=50] w2[y=90] mit2 r1[y=90] mit1 12 Lock Based Isolation ? Cursor Stability ? 2 Phase Write Lock on Row。 Cursor Stability Read Lock on Row ? Cursor Stability Case: ? Begin[x=50,y=50] RLock1[x] r1[x=50] r2[x=50] wlock2[x]
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