B-Tree Structure Modifications - Transaction Processing - page 202

Algorithm 8.10 Procedure redo-page-split .r/
if r is of the form “n Wh page-split ;p;q;x 0 ;q 0 ;s 0 ;V 0 ;hi” then
if R EC -LSN.p/ n then
fix-and-write-latch .p/
if page p is unmodified then
R EC -LSN.p/ maxfR EC -LSN.p/; P AGE -LSN.p/C1g
end if
if P AGE -LSN.p/ < n then
insert the index record .x 0 ;q 0 / into page p
P AGE -LSN.p/ n
end if
unlatch-and-unfix .p/
end if
if R EC -LSN.q/ n then
fix-and-write-latch .q/
if page q is unmodified then
R EC -LSN.q/ maxfR EC -LSN.q/; P AGE -LSN.q/ C1g
end if
if P AGE -LSN.q/ < n then
delete from page q all records with keys x 0
P AGE -LSN.q/ n
end if
unlatch-and-unfix .q/
end if
if R EC -LSN.q 0 / n then
fix-and-write-latch .q 0 /
if page q 0 is unmodified then
R EC -LSN.q 0 / maxfR EC -LSN.q 0 /; P AGE -LSN.q 0 /C1g
end if
if P AGE -LSN.q 0 /<n then
format page q 0 as an empty B-tree page of height h
insert the records in V 0 into page q 0
P AGE -LSN.q 0 / n
end if
unlatch-and-unfix .q 0 /
end if
if R EC -LSN.s 0 / n then
fix-and-write-latch .s 0 /
if page s 0 is unmodified then
R EC -LSN.s 0 / maxfR EC -LSN.s 0 /; P AGE -LSN.s 0 /C1g
end if
if P AGE -LSN.s 0 /<n then
mark page q 0 as allocated in page s 0
P AGE -LSN.s 0 / n
end if
unlatch-and-unfix .s 0 /
end if
end if