Exasol is an in memory database with parallel processing, or shorter MPP(Massively Parallel Processing) database. I got in touch with some people from Exasol at the DOAG 2019 in Nuremberg but never had the time to take a closer look since then. Over the past few weeks however I finally had the chance to get in touch with the system and thought it might be a good idea to share what I learned by writing a couple of blog posts. This is the first one in this series and I’ll start with the basics: Getting a test system up and running, and once it is there how to connect to it, with either a graphical user interface or by using the command line. In the coming post we’ll look at how Exasol handles transactions, how you can connect Exasol to PostgreSQL and how you can import and export data, and few other topics that differentiate Exasol from other database systems.
For getting a test system up and running you basically have three choices:
- Deployment in a private cloud
- Deployment in a public cloud (AWS, Azure, Google)
- Use the community edition (limited to 200GB of data but with all the features), either as an OVA file or as an ISO for installation
I went with the community edition and you can request a download here.
Once you either have installed from the ISO or imported the OVA you should see a screen like this which gives you the basic information you need to connect the system:
One graphical tool you can use to connect to Exasol is dbeaver. Setting up a connection to Exasol in dbeaver is just a matter of a few clicks:
Another option you have is the command line. The client is called EXAPlus and can be downloaded from the Exasol’s download page. The client is written in Java and should run on any operating system.
When start that up and connect the Exasol system you’ll notice that it pretty much feels like SQL*Plus from Oracle:
dwe@dwe:~/EXAplus-7.0.0$ ./exaplus -c 192.168.22.117:8563 -u sys -p exasol
EXAplus 7.0.0 (c) EXASOL AG
Monday, September 28, 2020 at 4:30:32 PM Central European Summer Time
Connected to database EXAone as user sys.
EXASolution 7.0.2 (c) EXASOL AG
SQL_EXA> select * from exa_parameters;
EXA: select * from exa_parameters;
PARAMETER_NAME
------------------------------
SESSION_VALUE
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SYSTEM_VALUE
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
NLS_DATE_FORMAT
YYYY-MM-DD
YYYY-MM-DD
NLS_FIRST_DAY_OF_WEEK
7
7
NLS_TIMESTAMP_FORMAT
YYYY-MM-DD HH24:MI:SS.FF6
YYYY-MM-DD HH24:MI:SS.FF6
NLS_NUMERIC_CHARACTERS
.,
.,
NLS_DATE_LANGUAGE
ENG
ENG
QUERY_TIMEOUT
0
0
CONSTRAINT_STATE_DEFAULT
ENABLE
ENABLE
PROFILE
OFF
OFF
TIME_ZONE
UTC
UTC
TIME_ZONE_BEHAVIOR
INVALID SHIFT AMBIGUOUS ST
INVALID SHIFT AMBIGUOUS ST
DEFAULT_CONSUMER_GROUP
MEDIUM
MEDIUM
NICE
OFF
OFF
SQL_PREPROCESSOR_SCRIPT
QUERY_CACHE
ON
ON
DEFAULT_LIKE_ESCAPE_CHARACTER
\
\
TIMESTAMP_ARITHMETIC_BEHAVIOR
INTERVAL
INTERVAL
SCRIPT_LANGUAGES
PYTHON=builtin_python R=builtin_r JAVA=builtin_java PYTHON3=builtin_python3
PYTHON=builtin_python R=builtin_r JAVA=builtin_java PYTHON3=builtin_python3
SCRIPT_OUTPUT_ADDRESS
PASSWORD_EXPIRY_POLICY
OFF
OFF
PASSWORD_SECURITY_POLICY
OFF
OFF
HASHTYPE_FORMAT
HEX
HEX
TEMP_DB_RAM_LIMIT
OFF
OFF
USER_TEMP_DB_RAM_LIMIT
OFF
OFF
SESSION_TEMP_DB_RAM_LIMIT
OFF
OFF
ST_MAX_DECIMAL_DIGITS
16
16
25 rows in resultset.
SQL_EXA> col session_value for a80;
COLUMN session_value ON
FORMAT a80
SQL_EXA> col system_value for a80;
COLUMN system_value ON
FORMAT a80
SQL_EXA> select * from exa_parameters;
EXA: select * from exa_parameters;
PARAMETER_NAME SESSION_VALUE SYSTEM_VALUE
------------------------------ -------------------------------------------------------------------------------- --------------------------------------------------------------------------------
NLS_DATE_FORMAT YYYY-MM-DD YYYY-MM-DD
NLS_FIRST_DAY_OF_WEEK 7 7
NLS_TIMESTAMP_FORMAT YYYY-MM-DD HH24:MI:SS.FF6 YYYY-MM-DD HH24:MI:SS.FF6
NLS_NUMERIC_CHARACTERS ., .,
NLS_DATE_LANGUAGE ENG ENG
QUERY_TIMEOUT 0 0
CONSTRAINT_STATE_DEFAULT ENABLE ENABLE
PROFILE OFF OFF
TIME_ZONE UTC UTC
TIME_ZONE_BEHAVIOR INVALID SHIFT AMBIGUOUS ST INVALID SHIFT AMBIGUOUS ST
DEFAULT_CONSUMER_GROUP MEDIUM MEDIUM
NICE OFF OFF
SQL_PREPROCESSOR_SCRIPT
QUERY_CACHE ON ON
DEFAULT_LIKE_ESCAPE_CHARACTER \ \
TIMESTAMP_ARITHMETIC_BEHAVIOR INTERVAL INTERVAL
SCRIPT_LANGUAGES PYTHON=builtin_python R=builtin_r JAVA=builtin_java PYTHON3=builtin_python3 PYTHON=builtin_python R=builtin_r JAVA=builtin_java PYTHON3=builtin_python3
SCRIPT_OUTPUT_ADDRESS
PASSWORD_EXPIRY_POLICY OFF OFF
PASSWORD_SECURITY_POLICY OFF OFF
HASHTYPE_FORMAT HEX HEX
TEMP_DB_RAM_LIMIT OFF OFF
USER_TEMP_DB_RAM_LIMIT OFF OFF
SESSION_TEMP_DB_RAM_LIMIT OFF OFF
ST_MAX_DECIMAL_DIGITS 16 16
25 rows in resultset.
SQL_EXA>
Even some of the parameters like the various “NLS_*” settings are the same than in Oracle. If I understood correctly, Exasol, in the beginning, was an accelerator on top of Oracle and that would explain why some aspects of the system are very close to it.
An Exasol database always contains two schemas, SYS and EXA_STATISTICS but you won’t see them in the corresponding system catalog view:
SQL_EXA> select * from EXA_DBA_SCHEMAS; EXA: select * from EXA_DBA_SCHEMAS; SCHEMA_NAME SCHEMA_OWNER SCHEMA_OBJECT_ID SCHEM SCHEMA_COMMENT --------------- --------------- --------------------- ----- ------------------------------ 0 rows in resultset.
Again, it pretty much feels like Oracle in the beginning. All the catalog views start with EXA_DBA_/EXA_USER_ or EXA_ALL_ (and yes, tab-completion works in EXAPlus):
SQL_EXA> select * from EXA_ Display all 143 possibilities? (y or n) EXA_ALL_COLUMNS EXA_ALL_VIRTUAL_TABLES EXA_DBA_RESTRICTED_OBJ_PRIVS EXA_MONITOR_DAILY EXA_STATISTICS EXA_USER_OBJ_PRIVS_MADE EXA_ALL_COLUMN_SIZES EXA_CACHE_CONTENT EXA_DBA_ROLES EXA_MONITOR_HOURLY EXA_STATISTICS_OBJECT_SIZES EXA_USER_OBJ_PRIVS_RECD EXA_ALL_CONNECTIONS EXA_CLUSTERS EXA_DBA_ROLE_PRIVS EXA_MONITOR_LAST_DAY EXA_SYSCAT EXA_USER_PROFILE_LAST_DAY EXA_ALL_CONSTRAINTS EXA_CONSUMER_GROUPS EXA_DBA_SCHEMAS EXA_MONITOR_MONTHLY EXA_SYSTEM_EVENTS EXA_USER_PROFILE_RUNNING EXA_ALL_CONSTRAINT_COLUMNS EXA_DBA_AUDIT_IMPERSONATION EXA_DBA_SCHEMA_OBJECTS EXA_OBJECTSTORAGE_USAGE EXA_SYS_COLUMNS EXA_USER_RESTRICTED_OBJ_PRIVS EXA_ALL_DEPENDENCIES EXA_DBA_AUDIT_SESSIONS EXA_DBA_SCRIPTS EXA_PARAMETERS EXA_SYS_SCRIPTS EXA_USER_ROLE_PRIVS EXA_ALL_FUNCTIONS EXA_DBA_AUDIT_SQL EXA_DBA_SESSIONS EXA_ROLE_CONNECTION_PRIVS EXA_TIME_ZONES EXA_USER_SCHEMAS EXA_ALL_INDICES EXA_DBA_COLUMNS EXA_DBA_SESSIONS_LAST_DAY EXA_ROLE_OBJ_PRIVS EXA_USAGE_DAILY EXA_USER_SCHEMA_OBJECTS EXA_ALL_OBJECTS EXA_DBA_COLUMN_SIZES EXA_DBA_SESSION_RESOURCES EXA_ROLE_RESTRICTED_OBJ_PRIVS EXA_USAGE_HOURLY EXA_USER_SCRIPTS EXA_ALL_OBJECT_SIZES EXA_DBA_CONNECTIONS EXA_DBA_SYS_PRIVS EXA_ROLE_ROLE_PRIVS EXA_USAGE_LAST_DAY EXA_USER_SESSIONS EXA_ALL_OBJ_PRIVS EXA_DBA_CONNECTION_PRIVS EXA_DBA_TABLES EXA_ROLE_SYS_PRIVS EXA_USAGE_MONTHLY EXA_USER_SESSIONS_LAST_DAY EXA_ALL_OBJ_PRIVS_MADE EXA_DBA_CONSTRAINTS EXA_DBA_TRANSACTION_CONFLICTS EXA_SCHEMAS EXA_USER_COLUMNS EXA_USER_SESSION_RESOURCES EXA_ALL_OBJ_PRIVS_RECD EXA_DBA_CONSTRAINT_COLUMNS EXA_DBA_USERS EXA_SCHEMA_OBJECTS EXA_USER_COLUMN_SIZES EXA_USER_SYS_PRIVS EXA_ALL_ROLES EXA_DBA_DEPENDENCIES EXA_DBA_VIEWS EXA_SESSION_CONNECTIONS EXA_USER_CONNECTION_PRIVS EXA_USER_TABLES EXA_ALL_SCHEMAS EXA_DBA_DEPENDENCIES_RECURSIVE EXA_DBA_VIRTUAL_COLUMNS EXA_SESSION_PRIVS EXA_USER_CONSTRAINTS EXA_USER_TRANSACTION_CONFLICTS_LAST_DAY EXA_ALL_SCHEMA_OBJECTS EXA_DBA_FUNCTIONS EXA_DBA_VIRTUAL_SCHEMAS EXA_SESSION_ROLES EXA_USER_CONSTRAINT_COLUMNS EXA_USER_USERS EXA_ALL_SCRIPTS EXA_DBA_IMPERSONATION_LAST_DAY EXA_DBA_VIRTUAL_SCHEMA_PROPERTIES EXA_SNAPSHOT_BACKUP EXA_USER_DEPENDENCIES EXA_USER_VIEWS EXA_ALL_SESSIONS EXA_DBA_IMPERSONATION_PRIVS EXA_DBA_VIRTUAL_TABLES EXA_SPATIAL_REF_SYS EXA_USER_FUNCTIONS EXA_USER_VIRTUAL_COLUMNS EXA_ALL_TABLES EXA_DBA_INDICES EXA_DB_SIZE_DAILY EXA_SQL_DAILY EXA_USER_IMPERSONATION_LAST_DAY EXA_USER_VIRTUAL_SCHEMAS EXA_ALL_USERS EXA_DBA_OBJECTS EXA_DB_SIZE_HOURLY EXA_SQL_HOURLY EXA_USER_IMPERSONATION_PRIVS EXA_USER_VIRTUAL_SCHEMA_PROPERTIES EXA_ALL_VIEWS EXA_DBA_OBJECT_SIZES EXA_DB_SIZE_LAST_DAY EXA_SQL_KEYWORDS EXA_USER_INDICES EXA_USER_VIRTUAL_TABLES EXA_ALL_VIRTUAL_COLUMNS EXA_DBA_OBJ_PRIVS EXA_DB_SIZE_MONTHLY EXA_SQL_LAST_DAY EXA_USER_OBJECTS EXA_VIRTUAL_SCHEMAS EXA_ALL_VIRTUAL_SCHEMAS EXA_DBA_PROFILE_LAST_DAY EXA_LOADAVG EXA_SQL_MONTHLY EXA_USER_OBJECT_SIZES EXA_VOLUME_USAGE EXA_ALL_VIRTUAL_SCHEMA_PROPERTIES EXA_DBA_PROFILE_RUNNING EXA_METADATA EXA_SQL_TYPES EXA_USER_OBJ_PRIVS SQL_EXA> select * from EXA_
The “SYS” schema contains all meta data definitions while the the EXA_STATISTICS schema contains monitoring and use statistics of the system, like EXA_MONITOR_HOURLY:
SQL_EXA> col cluster_name for a15; COLUMN cluster_name ON FORMAT a15 SQL_EXA> select INTERVAL_START,CLUSTER_NAME,LOAD_AVG,LOAD_MAX,CPU_AVG,CPU_MAX from EXA_MONITOR_HOURLY; EXA: select INTERVAL_START,CLUSTER_NAME,LOAD_AVG,LOAD_MAX,CPU_AVG,CPU_MAX f... INTERVAL_START CLUSTER_NAME LOAD_A LOAD_M CPU_AV CPU_MA -------------------------- --------------- ------ ------ ------ ------ 2020-09-28 08:00:00.000000 MASTER 0.4 2.3 2.1 4.7 2020-09-28 09:00:00.000000 MASTER 0.1 0.4 2.8 12.0 2020-09-28 10:00:00.000000 MASTER 0.0 0.3 1.9 6.8 2020-09-28 11:00:00.000000 MASTER 0.1 0.6 2.6 6.8 2020-09-28 12:00:00.000000 MASTER 0.0 0.3 2.5 7.2 2020-09-28 13:00:00.000000 MASTER 0.1 0.6 2.7 12.9 2020-09-28 14:00:00.000000 MASTER 0.0 0.2 2.1 6.3 2020-09-28 15:00:00.000000 MASTER 0.0 0.2 1.8 6.1 2020-09-28 16:00:00.000000 MASTER 0.0 0.2 2.1 6.3 9 rows in resultset.
When it comes to users and schemas Exasol compares more to PostgreSQL or SQL Server. A user can create multiple schemas and schemas can be owned by a user, e.g.:
SQL_EXA> create schema s1; EXA: create schema s1; Rows affected: 0 SQL_EXA> create schema s2; EXA: create schema s2; Rows affected: 0 SQL_EXA> create user u1 identified by "u1"; EXA: create user u1 identified by "u1"; Rows affected: 0 SQL_EXA> alter schema s1 change owner u1; EXA: alter schema s1 change owner u1; Rows affected: 0 SQL_EXA>
Now that we now how to setup a simple test system, how to connect and how the catalog is organized we can go into the details. But that will be the topic of the next post.
Cet article Getting started with Exasol – Setting up an environment est apparu en premier sur Blog dbi services.