| 1 | = 新 hbase 解析 = |
| 2 | * hbase 已經到0.19.3了,可惜的是 hbase 0.18.1的api及文件都已經從官方網頁被拿掉了,所幸hbase 0.18 與hbase 0.19相差無幾 |
| 3 | * hbase 0.1.3 到 hbase 0.19.3 中間好像已經包含了十幾代,但是其實類似java 1.4 直接跳躍 到 java 5 一樣,hbase 0.1.3 -> hbase 0.2.x -> hbase 0.18.x -> hbase 0.19.x |
| 4 | * 從 hbase 0.18.x 之後,其版本名稱就直接對應hadoop 的版本名稱,如 hbase 0.18 搭配 hadoop 0.18 , hbase 0.19 搭配hadoop 0.19 |
| 5 | * 筆者開發hbase時是 hbase 0.13的時代,現在又重拾舊業,發現已經差很多了。如 |
| 6 | * 找資料: |
| 7 | * hbase 0.13 : select * from 'table_name' |
| 8 | * hbase 0.19 : scan 'table_name' |
| 9 | * 資料庫結構: |
| 10 | * hbase 0.13 : |
| 11 | || || column_family:column_quolify1|| column_family:column_quolify2|| column_family:column_quolify3|| |
| 12 | || time stamp 2 || cell_value1 || cell_value2|| cell_value3|| |
| 13 | || time stamp 1 || cell_value1 || cell_value2|| cell_value3|| |
| 14 | * hbase 0.19 : 加入 row 這個結構 |
| 15 | |
| 16 | |
| 17 | |
| 18 | {{{ |
| 19 | #!java |
| 20 | |
| 21 | HBaseConfiguration config = new HBaseConfiguration(); |
| 22 | }}} |
| 23 | |
| 24 | {{{ |
| 25 | #!java |
| 26 | HBaseAdmin admin = new HBaseAdmin(config); |
| 27 | if (!admin.tableExists(table_name)) { |
| 28 | System.out.println("HTable : " + table_name |
| 29 | + " creating ... please wait"); |
| 30 | HTableDescriptor tableDesc = new HTableDescriptor(table_name); |
| 31 | // add column family |
| 32 | tableDesc.addFamily(new HColumnDescriptor(colomn_family)); |
| 33 | admin.createTable(tableDesc); |
| 34 | } |
| 35 | }}} |
| 36 | |
| 37 | {{{ |
| 38 | #!java |
| 39 | |
| 40 | |
| 41 | BatchUpdate batchUpdate = new BatchUpdate(hbase_row); |
| 42 | batchUpdate.put(colomn_family+column_quolify, Bytes.toBytes(value)); |
| 43 | batchUpdate.delete(colomn_family+"cellIWantDeleted"); |
| 44 | }}} |
| 45 | |
| 46 | {{{ |
| 47 | #!java |
| 48 | HTable table = new HTable(config, table_name); |
| 49 | table.commit(batchUpdate); |
| 50 | }}} |
| 51 | |
| 52 | {{{ |
| 53 | #!java |
| 54 | |
| 55 | Cell cell = table.get(hbase_row, colomn_family+column_quolify); |
| 56 | System.out.print(cell.getValue()); |
| 57 | |
| 58 | }}} |
| 59 | |
| 60 | {{{ |
| 61 | #!java |
| 62 | Scanner scanner = |
| 63 | table.getScanner(new String[] { colomn_family+column_quolify }); |
| 64 | |
| 65 | RowResult rowResult = scanner.next(); |
| 66 | |
| 67 | while (rowResult != null) { |
| 68 | |
| 69 | System.out.println("Found row: " |
| 70 | + Bytes.toString(rowResult.getRow()) |
| 71 | + " with value: " |
| 72 | + rowResult.get(Bytes |
| 73 | .toBytes(colomn_family+column_quolify))); |
| 74 | rowResult = scanner.next(); |
| 75 | } |
| 76 | |
| 77 | for (RowResult result : scanner) { |
| 78 | System.out.println("Found row: " |
| 79 | + Bytes.toString(rowResult.getRow()) |
| 80 | + " with value: " |
| 81 | + rowResult.get(Bytes |
| 82 | .toBytes(colomn_family+column_quolify))); |
| 83 | } |
| 84 | |
| 85 | scanner.close(); |
| 86 | |
| 87 | |
| 88 | |
| 89 | }}} |
| 90 | |
| 91 | |
| 92 | * 完整程式碼如下 |
| 93 | |