3. PostgreSQL general features (briefly)

7. Should the name be PostgreSQL or Postgres?

8. GPL vs BSD

9. Four legs Unix good, two legs Windows bad

10. emacs vs. vi

11. GUI vs command line

12. ...

14. tar -j -xf postgresql-8.4.1.tar.bz2

15. cd postgresql-8.4.1

16. ./configure –prefix=`pwd`/../pg84 --with-pgport=5678

17. make && make install && cd contrib && make && make install

19. myyearbook

20. Skype

21. Etsy

22. New York Post

23. Afilias

25. IMDB

26. Rockport

27. Apple

28. NTT

29. Cisco

30. National Weather Service

32. Wikipedia

33. Drupal

34. Bricolage

35. OpenACS

36. Gforge

38. Serendipity

39. PostGIS

40. OpenStreetMap

41. Reddit

42. Trac

43. LedgerSMB

44. PostgreSQL history Original Postgres project started at Berkeley 1986 by Michael Stonebraker SQL added in 1995 Current community project dates from 1996 Several developers from then still active, e.g. Bruce Momjian

46. Nobody owns the code, anyone can use the code

47. No monopoly

49. Safety

50. Correctness

51. Robustness

52. Standards compliance

53. Performance

56. Joins and Subqueries

57. Foreign keys

58. Namespaces (schemas)

59. Triggers

62. Point In Time Recovery

64. 17 months in development

65. Over 200 new features and improvements

67. Window Functions

68. Parallel Restore

70. Variadic functions

71. Per database locales

72. Significant performance improvements

73. Version aware psql command

75. with t as ( select a,b,c from foo ), s as (select a,d,e from bar) select b,d from t,s where t.a=s.a;

77.  354224848179261915075

79. Forget nested sets similar monstrosities

80. Interesting effects with CTEs create or replace function hanoi (discs integer, move out integer, a out int[], b out int[], c out int[]) returns setof record language sql as $$ with recursive han as ( select 1::int as move, $1 as ndiscs, '{99}'::int[] || array_agg(discs)as a, '{99}'::int[] as b, '{99}'::int[] as c from generate_series($1,1,-1) as discs union all select move + 1 , ndiscs, hnext(move, ndiscs, a,b,c), hnext(move, ndiscs, b,c,a), hnext(move, ndiscs, c,a,b) from han where array_length(b,1) < ndiscs + 1 ) select move, a[2:$1+1] as a, b[2:$1+1] as b, c[2:$1+1] as c from han order by move $$; Select * from hanoi(4);

81. Results: move | a | b | c ------+-----------+-----------+--------- 1 | {4,3,2,1} | {} | {} 2 | {4,3,2} | {} | {1} 3 | {4,3} | {2} | {1} 4 | {4,3} | {2,1} | {} 5 | {4} | {2,1} | {3} 6 | {4,1} | {2} | {3} 7 | {4,1} | {} | {3,2} 8 | {4} | {} | {3,2,1} 9 | {} | {4} | {3,2,1} 10 | {} | {4,1} | {3,2} 11 | {2} | {4,1} | {3} 12 | {2,1} | {4} | {3} 13 | {2,1} | {4,3} | {} 14 | {2} | {4,3} | {1} 15 | {} | {4,3,2} | {1} 16 | {} | {4,3,2,1} | {} (16 rows)

83. And similar for insert and update queries

85. Similar to aggregates, but does not collapse rows

86. All aggregate functions can be used as window functions

88. select *, row_number() over t as rownum from bar window t as (order by foo) order by foo

89. (you can omit the outer order by, but it's best not to).

92. merge

94. Only works with custom format dumps

95. Uses specified number of connections to the database

96. Especially useful for partitioned databases

97. Typical speedup is around number_of_processors/2

98. Sweet spot is between number_of_processors and 2 * number_of_processors

100. Individual steps are not parallelized

101. Uses dependency information to make sure steps are done in right order

102. Parallel clients are forked processes on *nix, threads on Windows

103. pg_restore -d dbname -j 4 dumpfile

108. All being addressed

110. Two efforts underway ...

116. Transparent to applications

118. New special built in WALsender daemon

119. After initial backup (rsync) all managed via config file settings

120. Streams log records rather than waiting for complete WAL files – much lower latency

123. Ideal for a report server, decision support etc.

124. Take load off transaction processing system

127. Previously only way to do this was via a view

128. In SQL Standard

130. Can be set at time of createdb instead of initdb

133. This trigger inhibits the update if the new and old records are identical

134. Very fast (uses memcmp() on whole data area)

135. Break even point is at worst around 30%, i.e. you're better off using it if more than 30% of the updates are in fact redundant.

136. Also save vacuuming etc.

140. Opposite of array_agg()

144. FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } ONLY

146. SELECT min($1[i]) FROM generate_subscripts($1, 1) g(i);

147. $$ LANGUAGE SQL; select mleast(1,4,9,-6,2,5);

148. Result: -6

150. Previously required overloading to get same effect.

153. Questions?