Postgresql：为什么“ILIKE”有时会区分大小写？

Question

我正在搜索这一行：

/**
 * PLUNKER VERSION (based on systemjs.config.js in angular.io)
 * System configuration for Angular 2 samples
 * Adjust as necessary for your application needs.
 */
(function(global) {

  var ngVer = '@2.0.0-rc.5'; // lock in the angular package version; do not let it float to current!
  var routerVer = '@3.0.0-rc.1'; // lock router version
  var formsVer = '@0.3.0'; // lock forms version
  var routerDeprecatedVer = '@2.0.0-rc.2'; // temporarily until we update all the guides

  //map tells the System loader where to look for things
  var map = {
    'app':                        'app',

    '@angular':                   'https://npmcdn.com/@angular', // sufficient if we didn't pin the version
    '@angular/router':            'https://npmcdn.com/@angular/router' + routerVer,
    '@angular/forms':             'https://npmcdn.com/@angular/forms' + formsVer,
    '@angular/router-deprecated': 'https://npmcdn.com/@angular/router-deprecated' + routerDeprecatedVer,
    'angular2-in-memory-web-api': 'https://npmcdn.com/angular2-in-memory-web-api', // get latest
    'rxjs':                       'https://npmcdn.com/rxjs@5.0.0-beta.6',
    'ts':                         'https://npmcdn.com/plugin-typescript@4.0.10/lib/plugin.js',
    'typescript':                 'https://npmcdn.com/typescript@1.9.0-dev.20160409/lib/typescript.js',
    '@angular2-material':         'node_modules/@angular2-material',
 };

  //packages tells the System loader how to load when no filename and/or no extension
  var packages = {
    'app':                        { main: 'main.ts',  defaultExtension: 'ts' },
    'rxjs':                       { defaultExtension: 'js' },
    'angular2-in-memory-web-api': { main: 'index.js', defaultExtension: 'js' },
    '@angular2-material/core': { 
        format: 'cjs',
        defaultExtension: 'js',
        main: 'core.js'
      },
      '@angular2-material/checkbox': { 
        main: 'checkbox.js', 
        defaultExtension: 'js', 
        format: 'cjs' 
      },
      '@angular2-material/button': { 
        main: 'button.js', 
        defaultExtension: 'js', 
        format: 'cjs' 
      },
      '@angular2-material/progress-circle': { 
        main: 'progress-circle.js', 
        defaultExtension: 'js', 
        format: 'cjs' 
      },
      '@angular2-material/card': { 
        main: 'card.js', 
        defaultExtension: 'js', 
        format: 'cjs' 
      },
      '@angular2-material/input': { 
        main: 'input.js', 
        defaultExtension: 'js', 
        format: 'cjs' 
      },
      '@angular2-material/toolbar': { 
        main: 'toolbar.js', 
        defaultExtension: 'js', 
        format: 'cjs' 
      },
      '@angular2-material/menu': { 
            main: 'menu.js', 
            defaultExtension: 'js', 
            format: 'cjs' 
      },
      '@angular2-material/icon': { 
            main: 'icon.js', 
            defaultExtension: 'js', 
            format: 'cjs' 
          }
  };

  var ngPackageNames = [
    'common',
    'compiler',
    'core',
    'http',
    'platform-browser',
    'platform-browser-dynamic',
    'upgrade',
  ];

  // Add map entries for each angular package
  // only because we're pinning the version with `ngVer`.
  ngPackageNames.forEach(function(pkgName) {
    map['@angular/'+pkgName] = 'https://npmcdn.com/@angular/' + pkgName + ngVer;
  });

  // Add package entries for angular packages
  ngPackageNames.concat(['forms', 'router', 'router-deprecated']).forEach(function(pkgName) {

    // Bundled (~40 requests):
    packages['@angular/'+pkgName] = { main: '/bundles/' + pkgName + '.umd.js', defaultExtension: 'js' };

    // Individual files (~300 requests):
    //packages['@angular/'+pkgName] = { main: 'index.js', defaultExtension: 'js' };
  });
  var config = {
    // DEMO ONLY! REAL CODE SHOULD NOT TRANSPILE IN THE BROWSER
    transpiler: 'ts',
    typescriptOptions: {
      tsconfig: true
    },
    meta: {
      'typescript': {
        "exports": "ts"
      }
    },
    map: map,
    packages: packages
  };

  System.config(config);

})(this);

这些查询成功找到它：

"c717e4d6-8db3-4c68-8c6f-f853c6c62312", "Аристотель", "source"

这个没找到它：

SELECT id, name, type FROM amt WHERE owner = '802f11da-c41c-4ad0-ae15-c7cf734c807f' AND name LIKE '%Ари%' limit 5;
SELECT id, name, type FROM amt WHERE owner = '802f11da-c41c-4ad0-ae15-c7cf734c807f' AND name ILIKE '%Ари%' limit 5;

如您所见，第二个和第三个查询之间的差异只有一个字母：“Ари”vs“ари”。

通常，SELECT id, name, type FROM amt WHERE owner = '802f11da-c41c-4ad0-ae15-c7cf734c807f' AND name ILIKE '%ари%' limit 5; 按预期工作，但在某些情况下，它无法正常搜索。我不知道为什么会这样。

当前数据库中的SQL窗格：

ILIKE