S3 Operador de límite de SQL

El operador de límite de SQL se utiliza para limitar el número de filas procesadas por la consulta.

Al alcanzar el límite establecido por el usuario, la Ceph Object Gateway deja de captar fragmentos adicionales.

A continuación se muestran ejemplos de operador de límite de SQL para CSV, Parquet y JSON.

CSV

[cephuser@host ~]$ aws s3api --endpoint-url http://extensa027.ceph.ibm.com:80 select-object-content  --bucket bkt1 --key placement_data1 --expression-type 'SQL' --input-serialization '{"CSV": {"FileHeaderInfo": "USE"}, "CompressionType": "NONE"}' --output-serialization '{"CSV": {}}' --expression "select * from s3object limit 10;" 

/dev/stdout
1,M,67.00,Others,91.00,Others,Commerce,58.00,Sci&Tech,No,55,Mkt&HR,58.8,Placed,270000
2,M,79.33,Central,78.33,Others,Science,77.48,Sci&Tech,Yes,86.5,Mkt&Fin,66.28,Placed,200000
3,M,65.00,Central,68.00,Central,Arts,64.00,Comm&Mgmt,No,75,Mkt&Fin,57.8,Placed,250000
4,M,56.00,Central,52.00,Central,Science,52.00,Sci&Tech,No,66,Mkt&HR,59.43,Not Placed,
5,M,85.80,Central,73.60,Central,Commerce,73.30,Comm&Mgmt,No,96.8,Mkt&Fin,55.5,Placed,425000
6,M,55.00,Others,49.80,Others,Science,67.25,Sci&Tech,Yes,55,Mkt&Fin,51.58,Not Placed,
7,F,46.00,Others,49.20,Others,Commerce,79.00,Comm&Mgmt,No,74.28,Mkt&Fin,53.29,Not Placed,
8,M,82.00,Central,64.00,Central,Science,66.00,Sci&Tech,Yes,67,Mkt&Fin,62.14,Placed,252000
9,M,73.00,Central,79.00,Central,Commerce,72.00,Comm&Mgmt,No,91.34,Mkt&Fin,61.29,Placed,231000
10,M,58.00,Central,70.00,Central,Commerce,61.00,Comm&Mgmt,No,54,Mkt&Fin,52.21,Not Placed,

Parquet

[cephuser@extensa022 ~]$ aws s3api --endpoint-url http://extensa027.ceph.ibm.com:80 select-object-content  --bucket parquetbkt2 --key smallfile --expression-type 'SQL' --input-serialization '{"Parquet": {}, "CompressionType": "NONE"}' --output-serialization '{"CSV": {}}'  --expression "select * from s3object limit 5;" 

/dev/stdout
4819,90340852.424672872,exile,0
4638,95603700.561133489,contradiction,1
1667,99440023.596563846,slam,2
7113,33213151.245887276,publisher,3
2872,43556628.954562038,demonstrate,4

JSON

[cephuser@extensa027 ~]$ aws s3api --endpoint-url http://extensa027.ceph.ibm.com:80 select-object-content  --bucket bkt1 --key books_data.json --expression-type 'SQL' --input-serialization '{"JSON": {"Type": "DOCUMENT"}, "CompressionType": "NONE"}' --output-serialization '{"CSV": {}}' --expression "select * from s3object[*];" 

/dev/stdout
id. : 1091
authors.name. : Makoto Satoh
authors.org. : Shinshu University
authors.id. : 2312688602
authors.name. : Ryo Muramatsu
authors.org. : Shinshu University
authors.id. : 2482909946
title. : Preliminary Design of a Network Protocol Learning Tool Based on the Comprehension of High School Students: Design by an Empirical Study Using a Simple Mind Map
year. : 2013
#=== 0 ===#
id. : 1388
authors.name. : Mizue Kayama
authors.org. : Shinshu University
authors.id. : 2128134587
authors.name. : Pranava K. Jha
authors.id. : 2718958994
authors.name. : Kazunori Itoh
authors.org. : Shinshu University
authors.id. : 2101782692
title. : Further Results on Independence in Direct-Product Graphs.
year. : 2000
#=== 1 ===#
id. : 5781
authors.name. : Jovan Dj. Golic
authors.id. : 1237859792
authors.name. : Guglielmo Morgari
authors.id. : 220887178
title. : Vectorial fast correlation attacks.
year. : 2004
#=== 2 ===#
id. : 6522
authors.name. : Güzin Ulutas
authors.org. : Karadeniz Technical Univ.
authors.id. : 2022192081
authors.name. : Mustafa Ulutas
authors.org. : Karadeniz Technical Univ.
authors.id. : 2023460672
authors.name. : Vasif V. Nabiyev
authors.org. : Karadeniz Technical Univ.
authors.id. : 2174205032
title. : Improved Secret Image Sharing Method By Encoding Shared Values With Authentication Bits
year. : 2011
#=== 3 ===#