Sangam 18 - Database Development: Return of the SQL Jedi

Copyright © 2017, Oracle and/or its affiliates. All rights reserved.
The Complete
Developer
Meaner, faster code via SQL!
1

Connor McDonald

Copyright © 2018, Oracle and/or its affiliates. All rights reserved. |
Stuff
youtube bit.ly/youtube-connor
blog bit.ly/blog-connor
twitter bit.ly/twitter-connor
400+ posts mainly on database & SQL
250 technical videos, new uploads every week
my thoughts on tech and the world :-)

etc...
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7
https://asktom.oracle.com

13
Java
html/css
node/angular
git/svn
logstash/MQ
Junit/Selenium
Cloud/REST/etc
etc
etc
etc

14
Java
html/css
node/angular
git/svn
logstash/MQ
Junit/Selenium
Cloud/REST/etc
???ORM Containers
KubernetesDocker

we developers love cool stuff
20

23
"fine-grained to perform a single function"
"Each service is ... minimal, and complete"
https://en.wikipedia.org/wiki/Microservices
select COUNT(*)
from PEOPLE
where GENDER = 'MALE'

27
"By abstracting the underlying implementation"
"describes the expected behaviour ... but can have multiple implementations"
https://en.wikipedia.org/wiki/Application_programming_interface
select NAME, STREET_NO, ZIP_CODE
from PEOPLE p,
ADDRESS a
where p.AGE > 50
and p.ADDRESS_ID = a.ADDRESS_ID;

... faster, simpler, better applications
32

33
Java
html/css
node/angular
git/svn
logstash/MQ
Junit/Selenium
Cloud/REST/etc
SQL
Database

... do two things with data
35

a quick primer on (database) memory

memory access = controlled access

SGA
protected by
2) access memory

SGA
protected by
3) release latch

SGA
protected by
someone must wait ...

spinning
can I have the latch ?
59

you ... get ... nothing ... done

“But how is that related
to reading data?”

to read data, you read blocks...

SQL> select *
2 from EMP
3 where ...
/d01/ts/my_data1.dat
Cache

but (database) memory access is complex
70
multi-process

SQL> select *
2 from EMP
3 where …
SQL> update EMP
2 set …
3 where …
SQL> select *
2 from EMP
3 where …
SQL> insert into
2 EMP
3 values (…)
SQL> select *
2 from CUSTOMER
3 /
SQL> select max(EMP)
2 from DEPT
SQL> delete
2 from DEPT
3 /

• Get latch
• Search along list of blocks in memory (or "chain")
• Read block
• Extract row of interest
• Release latch
• Give row back to client
"fetch a row"
74

rs = stmt.executeQuery("...");
while(rs.next()) {
v1 = rs.getInt(1);
v2 = rs.getString(2);
...
}
• Get latch
• Walk along chain
• Get block
• Extract single row
• Release latch
• Give row back to client
• Get latch (again)
• Walk along chain (again)
• Get block (again)
• Release latch (again)
• Give row back to client (again)
Row #1
Row #2
• Get latch (again)
• Walk along chain (again)
• Get block (again)
• Release latch (again)
• Give row back to client (again)
Row #3
78

a better strategy.... “pinning”

"fetch a row"
• Get latch
• Get block
• Pin the block
• Release latch
• Give row 1 back to client
• Give row 2 back to client
…
• Give row n to client
• Get latch
• Remove my pin on the block
• Release latch
“and .. I’ll will need
several rows from
this block”

how do you say
“I may want many rows” ?

DBA relationship is important
88
oc00.sql

Statistics
-------------------------------
13 recursive calls
1 db block gets
527 consistent gets
91
Statistics
------------------------------
0 recursive calls
0 db block gets
377 consistent gets
versus

... is one we've never seen
93

Syntax
Validity
Optimization
Rowsourcing
Execution
(Fetch)
SQL> select *
2 frmo emp;
frmo emp
*
ERROR at line 2:
ORA-00923: FROM keyword not found where expected
95

Syntax
Validity
Optimization
Rowsourcing
Execution
(Fetch)
SQL> select empnoo
2 from emp;
select empnoo
*
ERROR at line 1:
ORA-00904: invalid column name

Syntax
Validity
Optimization
Rowsourcing
Execution
(Fetch)
PLAN
-------------------------------------
SELECT STATEMENT
TABLE ACCESS BY INDEX ROWID EMP
INDEX RANGE SCAN EMP_PK

EMP_PK EMP
Syntax
Validity
Optimization
Rowsourcing
Execution
(Fetch)

Syntax
Validity
Optimization
Rowsourcing
Execution
(Fetch)
99

Syntax
Validity
Optimization
Rowsourcing
Execution
(Fetch)

could be most of execution time

SQL> select name, gets
2 from v$latch
3 where name like 'library%' or name like 'shared%';
NAME GETS
------------------------------ ----------
shared pool 333907
shared pool simulator 7191
shared pool sim alloc 133
shared server configuration 6
shared server info 1
SQL> select 0 from dual;
0
----------
0
GETS
----------
333991 = 84
7196 = 5
135 = 2
6
1

previously executed statements
107

select surname, firstname from emp where empno = 123
probability of reuse low ?

select surname, firstname from emp where empno = ?
binding
parse this...
now run it with ? = 7362
now run it with ? = 123

let's make it real
ParseDemo2 nn
ParseDemo2Bind nn

it takes 5 minutes to hack you

think blocks not rows
121
when appropriate

commit when it makes sense to
122

demo
123
InsertDemo3
InsertDemo4 nn

the default data access language
134

135
Hive
Spark
Tez
Presto
Drill
Hawq
Cloudera
Vertica
BigSQL
Jethro

ksql> CREATE STREAM ATM_TXNS (
account_id VARCHAR,
atm VARCHAR,
location STRUCT,
amount INT,
transaction_id VARCHAR)
WITH (
KAFKA_TOPIC='atm_txns',
VALUE_FORMAT='JSON');
ksql> SELECT ACCOUNT_ID, TRANSACTION_ID, AMOUNT, ATM FROM ATM_TXNS;
137

Thank you
youtube bit.ly/youtube-connor
blog connor-mcdonald.com
twitter @connor_mc_d

Sangam 18 - Database Development: Return of the SQL Jedi

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