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Remove useless whitespace at end of lines

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Peter Eisentraut
2010-11-23 22:27:50 +02:00
parent 44475e782f
commit fc946c39ae
517 changed files with 3463 additions and 3508 deletions
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52
src/backend/access/gist/README
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@ -24,21 +24,21 @@ The current implementation of GiST supports:
* Concurrency
* Recovery support via WAL logging
The support for concurrency implemented in PostgreSQL was developed based on
the paper "Access Methods for Next-Generation Database Systems" by
The support for concurrency implemented in PostgreSQL was developed based on
the paper "Access Methods for Next-Generation Database Systems" by
Marcel Kornaker:
http://www.sai.msu.su/~megera/postgres/gist/papers/concurrency/access-methods-for-next-generation.pdf.gz
The original algorithms were modified in several ways:
* They should be adapted to PostgreSQL conventions. For example, the SEARCH
algorithm was considerably changed, because in PostgreSQL function search
should return one tuple (next), not all tuples at once. Also, it should
* They should be adapted to PostgreSQL conventions. For example, the SEARCH
algorithm was considerably changed, because in PostgreSQL function search
should return one tuple (next), not all tuples at once. Also, it should
release page locks between calls.
* Since we added support for variable length keys, it's not possible to
guarantee enough free space for all keys on pages after splitting. User
defined function picksplit doesn't have information about size of tuples
* Since we added support for variable length keys, it's not possible to
guarantee enough free space for all keys on pages after splitting. User
defined function picksplit doesn't have information about size of tuples
(each tuple may contain several keys as in multicolumn index while picksplit
could work with only one key) and pages.
* We modified original INSERT algorithm for performance reason. In particular,
@ -67,7 +67,7 @@ gettuple(search-pred)
ptr = top of stack
while(true)
latch( ptr->page, S-mode )
if ( ptr->page->lsn != ptr->lsn )
if ( ptr->page->lsn != ptr->lsn )
ptr->lsn = ptr->page->lsn
currentposition=0
if ( ptr->parentlsn < ptr->page->nsn )
@ -88,7 +88,7 @@ gettuple(search-pred)
else if ( ptr->page is leaf )
unlatch( ptr->page )
return tuple
else
else
add to stack child page
end
currentposition++
@ -99,20 +99,20 @@ gettuple(search-pred)
Insert Algorithm
----------------
INSERT guarantees that the GiST tree remains balanced. User defined key method
Penalty is used for choosing a subtree to insert; method PickSplit is used for
the node splitting algorithm; method Union is used for propagating changes
INSERT guarantees that the GiST tree remains balanced. User defined key method
Penalty is used for choosing a subtree to insert; method PickSplit is used for
the node splitting algorithm; method Union is used for propagating changes
upward to maintain the tree properties.
NOTICE: We modified original INSERT algorithm for performance reason. In
NOTICE: We modified original INSERT algorithm for performance reason. In
particularly, it is now a single-pass algorithm.
Function findLeaf is used to identify subtree for insertion. Page, in which
insertion is proceeded, is locked as well as its parent page. Functions
findParent and findPath are used to find parent pages, which could be changed
because of concurrent access. Function pageSplit is recurrent and could split
page by more than 2 pages, which could be necessary if keys have different
lengths or more than one key are inserted (in such situation, user defined
Function findLeaf is used to identify subtree for insertion. Page, in which
insertion is proceeded, is locked as well as its parent page. Functions
findParent and findPath are used to find parent pages, which could be changed
because of concurrent access. Function pageSplit is recurrent and could split
page by more than 2 pages, which could be necessary if keys have different
lengths or more than one key are inserted (in such situation, user defined
function pickSplit cannot guarantee free space on page).
findLeaf(new-key)
@ -143,7 +143,7 @@ findLeaf(new-key)
end
findPath( stack item )
push stack, [root, 0, 0] // page, LSN, parent
push stack, [root, 0, 0] // page, LSN, parent
while( stack )
ptr = top of stack
latch( ptr->page, S-mode )
@ -152,7 +152,7 @@ findPath( stack item )
end
for( each tuple on page )
if ( tuple->pagepointer == item->page )
return stack
return stack
else
add to stack at the end [tuple->pagepointer,0, ptr]
end
@ -160,12 +160,12 @@ findPath( stack item )
unlatch( ptr->page )
pop stack
end
findParent( stack item )
parent = item->parent
latch( parent->page, X-mode )
if ( parent->page->lsn != parent->lsn )
while(true)
while(true)
search parent tuple on parent->page, if found the return
rightlink = parent->page->rightlink
unlatch( parent->page )
@ -214,7 +214,7 @@ placetopage(page, keysarray)
keysarray = [ union(keysarray) ]
end
end
insert(new-key)
stack = findLeaf(new-key)
keysarray = [new-key]
@ -236,4 +236,4 @@ insert(new-key)
Authors:
Teodor Sigaev <teodor@sigaev.ru>
Oleg Bartunov <oleg@sai.msu.su>
Oleg Bartunov <oleg@sai.msu.su>