Before running the following examples, perform the steps in Setting Up to Run the Examples, if not already done.
Replace the variables in the example code, such as YOUR-STORAGE-ACCOUNT, with appropriate values. See Variable Substitutions for Examples.
Using SHOW AUTHORIZATION
SHOW AUTHORIZATION NOS_USR.DefAuth;
If the authorization object does not exist, run the steps in Setting Up to Run the Examples.
Setting Up to Run CSV Examples
CREATE FOREIGN TABLE riverflow_csv
, EXTERNAL SECURITY DEFINER TRUSTED DefAuth
( Location VARCHAR(2048) CHARACTER SET UNICODE CASESPECIFIC,
Payload DATASET INLINE LENGTH 64000 STORAGE FORMAT CSV
)
USING (LOCATION('YOUR-STORAGE-ACCOUNT'));
Sampling External Data In Place Using READ_NOS
SELECT TOP 2 payload..* FROM READ_NOS_FM (
ON ( SELECT CAST( NULL AS DATASET STORAGE FORMAT CSV ) )
USING
LOCATION('YOUR-STORAGE-ACCOUNT')
RETURNTYPE('NOSREAD_RECORD')
) AS D;
Sample result:
Payload..* ------------------------------------------------------------------ ["11.6","10000","09380000","2018-07-01 00:00","662","0.00","8.65"] ["10.6","17600","09380000","2018-07-03 00:00","674","0.00","10.23"]
Sampling External Data In Place Using a Foreign Table
SELECT TOP 2 payload FROM riverflow_csv;
Sample result:
Payload ----------------------------------------------------------------------------------- BatteryVoltage,Flow,site_no,datetime,Precipitation,GageHeight ,0.00,09400815,2018-07-12 00:15,0.00,-0.01 BatteryVoltage,Flow,site_no,datetime,Precipitation,GageHeight ,0.00,09400815,2018-07-12 00:45,0.00,-0.01
Using DATASET_KEYS to See Header Names
SELECT DISTINCT * FROM DATASET_KEYS (ON (SELECT payload FROM riverflow_csv)) AS csvKeys;
Sample result:
DatasetKeys ----------------- Precipitation BatteryVoltage Temp Velocity Conductance WaterVelocity site_no GageHeight Flow GageHeight2 datetime
Finding Maximum and Minimum Values
SELECT MAX(CAST(payload..Flow AS FLOAT) ( FORMAT '-ZZZZ9.99'))
, MIN(CAST(payload..Flow AS FLOAT) ( FORMAT '-(5)ZZZ9.99'))
FROM riverflow_csv;
Sample result:
Maximum(Payload..Flow) Minimum(Payload..Flow)
---------------------- ----------------------
19000.00 -9.72
Querying for a Specific Set of Rows
SELECT MAX(CAST(payload..Flow AS FLOAT) ( FORMAT '-ZZZZ9.99')) FROM riverflow_csv WHERE payload..site_no = '09394500';
Sample result:
Maximum(Payload..Flow)
----------------------
1230.00
Previewing Data Using READ_NOS
SELECT TOP 2 payload FROM READ_NOS_FM (
ON ( SELECT CAST( NULL AS DATASET STORAGE FORMAT CSV ) )
USING
LOCATION('YOUR-STORAGE-ACCOUNT')
RETURNTYPE('NOSREAD_RECORD')
) AS D;
Sample result:
Payload --------------------------------------------------------------------------------- Temp,Flow,site_no,datetime,Conductance,Precipitation,GageHeight 11.4,11400,09380000,2018-07-02 00:00,654,0.00,8.97 Temp,Flow,site_no,datetime,Conductance,Precipitation,GageHeight 10.6,17600,09380000,2018-07-03 00:00,674,0.00,10.23
Viewing the Key Structure
SELECT TOP 2 LOCATION FROM READ_NOS_FM(
USING
RETURNTYPE('NOSREAD_KEYS')
LOCATION('YOUR-STORAGE-ACCOUNT')
) AS D;
Sample result:
Location ------------------------------------------------------------ /S3/td-usgs.s3.amazonaws.com/CSVDATA/09380000/2018/07/02.csv /S3/td-usgs.s3.amazonaws.com/CSVDATA/09380000/2018/07/03.csv
Loading External Data into the Database Using CREATE TABLE AS...WITH DATA
CREATE MULTISET TABLE riverflowprecip_csv AS ( SELECT CAST(payload..site_no AS CHAR(8)) SiteNo, CAST(payload..Flow AS FLOAT) Flow, CAST(payload..GageHeight AS FLOAT) GageHeight FROM riverflow_csv WHERE payload..Precipitation > 0 ) WITH DATA NO PRIMARY INDEX;
Display the number of rows in the table:
SELECT COUNT(*) FROM riverflowprecip_csv;
Sample result:
Count(*)
-----------
396
See Loading External Data into the Database Using CREATE TABLE AS...WITH DATA.
Loading External Data into the Database Using READ_NOS and CREATE TABLE AS
CREATE MULTISET TABLE riverflowperm_csv AS
(
SELECT
CAST(payload..site_no AS CHAR(8)) Site_no,
CAST(payload..Flow AS FLOAT) Flow,
CAST(payload..GageHeight AS FLOAT) GageHeight1,
CAST(payload..Precipitation AS FLOAT) Precipitation,
CAST(payload..Temp AS FLOAT) Temperature,
CAST(payload..Velocity AS FLOAT) Velocity
FROM READ_NOS_FM (
ON (SELECT CAST(NULL AS DATASET STORAGE FORMAT CSV))
USING
LOCATION('YOUR-STORAGE-ACCOUNT')
) AS D
) WITH DATA;
Display the number of rows in the table:
SELECT COUNT (*) FROM riverflowperm_csv;
Sample result:
Count(*)
-----------
36301
See Loading External Data into the Database Using READ_NOS and CREATE TABLE AS.
Loading External Data into the Database Using INSERT SELECT
CREATE TABLE RiverFlowPermInsert_csv (DateTS CHAR(20) ,SiteNo CHAR(8) ,Flow FLOAT FORMAT '-ZZZZ9.99' ,Velocity FLOAT FORMAT '-ZZZ9.99' ,GageHeight FLOAT FORMAT '-ZZZ9.99' ,Temp FLOAT FORMAT '-ZZZ9.99') PRIMARY INDEX (SiteNo);
Insert the external data into the database table:
INSERT INTO RiverFlowPermInsert_csv SELECT payload..datetime ,payload..site_no ,Cast (payload..Flow AS FLOAT) ,Cast (payload..Velocity AS FLOAT) ,Cast (payload..GageHeight AS FLOAT) ,Cast (payload..Temp AS FLOAT) WHERE payload..site_no = '09429070' FROM riverflow_csv;
Query the data from the database table:
SELECT TOP 2 * FROM RiverFlowPermInsert_csv;
Sample result:
DateTS SiteNo Flow Velocity GageHeight Temp -------------------- -------- -------- -------- ---------- ------- 2018-07-02 01:00 09429070 149.00 0.78 5.75 78.80 2018-07-02 00:30 09429070 145.00 0.77 5.68 78.90
See Loading External Data into the Database Using INSERT SELECT.
Joining External Data and Database Tables
Create a database dimension table to join to:
CREATE SET TABLE rivernames(
site_no CHAR(8) CHARACTER SET LATIN NOT CASESPECIFIC,
name CHAR(60) CHARACTER SET LATIN NOT CASESPECIFIC)
UNIQUE PRIMARY INDEX ( site_no ) ;
Create the foreign table or ask your database administrator to create the foreign table that is used to populate the dimension table:
CREATE FOREIGN TABLE nos_rivernames
, EXTERNAL SECURITY DEFINER TRUSTED DefAuth
( Location VARCHAR(2048) CHARACTER SET UNICODE CASESPECIFIC,
PAYLOAD DATASET INLINE LENGTH 64000 STORAGE FORMAT CSV
)
USING (
LOCATION('/s3/td-usgs.s3.amazonaws.com/RIVERS/rivers.csv')
);
Populate the dimension table:
INSERT INTO rivernames SELECT payload..site_no, payload..name FROM nos_rivernames;
Join the dimension table and external data (foreign table):
SELECT DISTINCT name(CHAR(60)) FROM riverflow_csv rf, rivernames rn WHERE rf.payload..site_no = rn.site_no AND rf.payload..Precipitation > 0.1 ORDER BY 1;
Sample result:
name ---------------------------------- CIBECUE CREEK NEAR OVERGAARD COLORADO RIVER AT LEES FERRY GILA RIVER AT KELVIN LITTLE COLORADO RIVER AT WOODRUFF NEW RIVER NEAR ROCK SPRINGS NEWMAN CANYON ABOVE UPPER LAKE MARY POLACCA WASH NEAR SECOND MESA PUERCO RIVER NEAR CHAMBERS SALT RIVER NEAR CHRYSOTILE SANTA MARIA RIVER NEAR BAGDAD
Filtering Using A Path Filter in the CREATE FOREIGN TABLE Definition
CREATE FOREIGN TABLE riverflow_csv_pathfilter
, EXTERNAL SECURITY DEFINER TRUSTED DefAuth (
Location VARCHAR(2048) CHARACTER SET UNICODE CASESPECIFIC,
Payload DATASET INLINE LENGTH 64000 STORAGE FORMAT CSV
)
USING
(
LOCATION ('YOUR-STORAGE-ACCOUNT/site_no')
PATHPATTERN('$data/$siteno/$year/$month/$day') );
Where site_no is a site number value; for example, 0938.
Show the table definition:
SHOW TABLE riverflow_csv_pathfilter;
See Filtering Using a Path Filter in the CREATE FOREIGN TABLE Definition.
Filtering on the Payload Column of a Foreign Table
Create a foreign table or ask your database administrator to create the foreign table using a custom PATHPATTERN:
CREATE FOREIGN TABLE riverflow_csv_path
, EXTERNAL SECURITY DEFINER TRUSTED DefAuth (
Location VARCHAR(2048) CHARACTER SET UNICODE CASESPECIFIC,
Payload DATASET INLINE LENGTH 64000 STORAGE FORMAT CSV
)
USING
(
LOCATION ('YOUR-STORAGE-ACCOUNT')
PATHPATTERN('$data/$siteno/$year/$month/$day') );
Run a query using a payload filter only:
SELECT TOP 2 CAST(payload..GageHeight AS FLOAT)( FORMAT '-ZZZ9.99') TheGageHeight, CAST (payload..Flow AS FLOAT)(FORMAT '-ZZZ9999.99') TheFlow FROM riverflow_csv_path WHERE payload..site_no = '09380000';
Sample result:
TheGageHeight TheFlow
------------- -----------
10.21 17500.00
10.20 17400.00
Run a similar query using equivalent path values in the filter:
SELECT TOP 2 CAST(payload..GageHeight AS FLOAT)( FORMAT '-ZZZ9.99') TheGageHeight, CAST (payload..Flow AS FLOAT)(FORMAT '-ZZZ9999.99') TheFlow FROM riverflow_csv_path WHERE $path.$siteno = '09380000';
Sample result:
TheGageHeight TheFlow
------------- -----------
10.16 17200.00
10.22 17500.00
Querying a Foreign Table with Path Filtering
Use path filtering to narrow down search results:
SELECT TOP 2 payload..* FROM riverflow_csv_path WHERE $PATH.$year = '2018' AND $PATH.$month = '07' AND $PATH.$day = '01.csv' AND $PATH.$siteno = '09400815';
Sample result:
Payload..* ---------------------------------------------------------- [null,"0.00","09400815","2018-07-01 00:15","0.00","-0.01"] [null,"0.00","09400815","2018-07-01 00:45","0.00","-0.01"]
Combining Path and Payload Filtering
Combine path and payload filtering:
SELECT COUNT(*) FROM riverflow_csv_path WHERE payload..GageHeight > 9.5 AND $path.$siteno = 09380000 AND $path.$year = '2018' AND $path.$month = '06';
Sample result:
Count(*)
-----------
185
Creating a Basic View
Create the view of the foreign table:
CREATE VIEW riverflowview_csv AS ( SELECT CAST(payload..Flow AS FLOAT) ( FORMAT '-ZZZZ9.99') Flow, CAST(payload..GageHeight AS FLOAT) ( FORMAT '-ZZZ9.99') GageHeight1, CAST(payload..Precipitation AS FLOAT) ( FORMAT '-ZZZ9.99') Precipitation, CAST(payload..Temp AS FLOAT) ( FORMAT '-ZZZ9.99') Temperature, CAST(payload..Velocity AS FLOAT) ( FORMAT '-ZZZ9.99') Velocity, CAST(payload..BatteryVoltage AS FLOAT) ( FORMAT '-ZZZ9.99') BatteryVoltage, CAST(payload..GageHeight2 AS FLOAT) ( FORMAT '-ZZZ9.99') GageHeight2 FROM riverflow_csv_path );
Query the view:
SELECT TOP 2 * FROM riverflowview_csv;
Sample result:
Flow GageHeight1 Precipitation Temperature Velocity BatteryVoltage GageHeight2 ------ ----------- ------------- ----------- -------- -------------- ----------- 186.00 2.05 ? ? ? ? 2.05 232.00 2.16 0.00 ? ? ? 2.16
Using Path Variables as Columns in a View
REPLACE VIEW riverflowview_csv AS ( SELECT CAST($path.$siteno AS CHAR(10)) TheSite, CAST($path.$year AS CHAR(4)) TheYear, CAST($path.$month AS CHAR(2)) TheMonth, CAST(SUBSTR($path.$day, 1, 2) AS CHAR(2)) TheDay, CAST(payload..Flow AS FLOAT) ( FORMAT '-ZZZZ9.99') Flow, CAST(payload..GageHeight AS FLOAT) ( FORMAT '-ZZZ9.99') GageHeight1, CAST(payload..Precipitation AS FLOAT) ( FORMAT '-ZZZ9.99') Precipitation, CAST(payload..Temp AS FLOAT) ( FORMAT '-ZZZ9.99') Temperature, CAST(payload..Velocity AS FLOAT) ( FORMAT '-ZZZ9.99') Velocity, CAST(payload..BatteryVoltage AS FLOAT) ( FORMAT '-ZZZ9.99') BatteryVoltage, CAST(payload..GageHeight2 AS FLOAT) ( FORMAT '-ZZZ9.99') GageHeight2 FROM riverflow_csv_path);
Using a Foreign Table View with Path Filtering
Replace the view of the foreign table:
REPLACE VIEW riverflowview_csv AS ( SELECT CAST($path.$siteno AS CHAR(10)) TheSite, CAST($path.$year AS CHAR(4)) TheYear, CAST($path.$month AS CHAR(2)) TheMonth, CAST(SUBSTR($path.$day, 1, 2) AS CHAR(2)) TheDay, CAST(payload..Flow AS FLOAT) ( FORMAT '-ZZZZ9.99') Flow, CAST(payload..GageHeight AS FLOAT) ( FORMAT '-ZZZ9.99') GageHeight1, CAST(payload..Precipitation AS FLOAT) ( FORMAT '-ZZZ9.99') Precipitation, CAST(payload..Temp AS FLOAT) ( FORMAT '-ZZZ9.99') Temperature, CAST(payload..Velocity AS FLOAT) ( FORMAT '-ZZZ9.99') Velocity, CAST(payload..BatteryVoltage AS FLOAT) ( FORMAT '-ZZZ9.99') BatteryVoltage, CAST(payload..GageHeight2 AS FLOAT) ( FORMAT '-ZZZ9.99') GageHeight2 FROM riverflow_csv_path WHERE TheSite = payload..site_no);
Query the view:
SELECT TOP 2 * FROM riverflowview_csv;
Sample result:
TheSite TheYear TheMonth TheDay Site_no Flow GageHeight1 Precipitation Temperature Velocity BatteryVoltage -------- ------- -------- ------ ----------- ------ ----------- ------------- ----------- -------- -------------- 09396100 2018 07 16 09396100 24.40 1.33 0.00 ? ? ? 09396100 2018 07 16 09396100 113.00 1.83 0.00 ? ? ?
Filter the view:
SELECT thesite,COUNT(*) FROM riverflowview_csv WHERE thesite='09396100' GROUP BY 1;
Sample result:
TheSite Count(*) ---------- ----------- 09396100 3086
Run EXPLAIN on the query to see how the filtering is done:
EXPLAIN SELECT thesite,COUNT(*) FROM riverflowview_csv WHERE thesite='09396100' GROUP BY 1;
Sample result:
Explanation
--------------------------------------------------------------------------
[…]
3) We do a single-AMP RETRIEVE step from OB.riverflow_csv_path in
view riverflowview_csv metadata by way of an all-rows scan with a
condition of ("(TD_SYSFNLIB.NosExtractVarFromPath (
OB.riverflow_csv_path in view riverflowview_csv.Location,
'/s3/s3.amazonaws.com/td-usgs', 2 )(CHAR(10), CHARACTER SET
UNICODE, NOT CASESPECIFIC))= '09396100 '") into Spool 3 (all_amps),
which is built locally on that AMP. Then we do a SORT to order
Spool 3 by the sort key as the field_id list( 3, 2). The size of
Spool 3 is estimated with no confidence to be 38 rows (26,790
bytes). The estimated time for this step is 0.55 seconds.
4) We do an all-AMPs RETRIEVE step in TD_Map1 from Spool 3 (Last Use)
by way of an all-rows scan into Spool 2 (all_amps), which is
binpacked and redistributed by size to all AMPs in TD_Map1. The
size of Spool 2 is estimated with no confidence to be 38 rows (
27,094 bytes). The estimated time for this step is 0.08 seconds.
5) We do an all-AMPs SUM step in TD_MAP1 to aggregate from
OB.riverflow_csv_path in view riverflowview_csv
by way of external metadata in Spool 2 (Last Use) with a condition
of ("(TD_SYSFNLIB.NosExtractVarFromPath (OB.riverflow_csv_path in
view riverflowview_csv.Location, '/s3/td-usgs.s3.amazonaws.com/', 2
)(CHAR(10), CHARACTER SET UNICODE, NOT CASESPECIFIC))=
(TRANSLATE((OB.riverflow_csv_path in view
riverflowview_csv.Payload .EXTRACTVALUE (
'242E2E736974655F6E6F'XB(VARBYTE(63000)), 'list'(VARCHAR(20),
CHARACTER SET LATIN, NOT CASESPECIFIC)))USING LATIN_TO_UNICODE))"),
and the grouping identifier in field 1. Aggregate Intermediate
Results are computed globally, then placed in Spool 5 in TD_Map1.
The size of Spool 5 is estimated with no confidence to be 504 rows
(706,608 bytes). The estimated time for this step is 0.32 seconds.
[…]