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1 /*
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2 Copyright (c) 2008 Franklin Schmidt <fschmidt@gmail.com>
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3
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4 Permission is hereby granted, free of charge, to any person obtaining a copy
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5 of this software and associated documentation files (the "Software"), to deal
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6 in the Software without restriction, including without limitation the rights
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7 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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8 copies of the Software, and to permit persons to whom the Software is
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9 furnished to do so, subject to the following conditions:
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10
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11 The above copyright notice and this permission notice shall be included in
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12 all copies or substantial portions of the Software.
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13
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14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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15 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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16 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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17 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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18 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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19 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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20 THE SOFTWARE.
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21 */
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22
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23 package fschmidt.util.servlet;
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24
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25 import java.sql.Connection;
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26 import java.sql.PreparedStatement;
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27 import java.sql.ResultSet;
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28 import java.sql.SQLException;
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29 import java.sql.Statement;
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30 import java.util.Date;
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31 import java.util.Map;
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32 import java.util.HashMap;
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33 import fschmidt.db.DbDatabase;
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34 import fschmidt.db.postgres.DbDatabaseImpl;
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35
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36
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37 public final class DbCache implements HttpCache {
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38 private final DbDatabase db;
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39 private long lastClear;
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40 private static final String LAST_CLEAR = "_last_clear";
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41
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42 public DbCache(DbDatabase db) {
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43 this.db = db;
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44 setLastClear();
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45 }
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46
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47 private void setLastClear() {
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48 try {
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49 Connection con = db.getConnection();
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50 try {
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51 PreparedStatement stmt = con.prepareStatement(
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52 "select last_modified from http_cache where event=?"
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53 );
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54 stmt.setString(1,LAST_CLEAR);
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55 ResultSet rs = stmt.executeQuery();
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56 if( !rs.next() ) {
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57 modified(LAST_CLEAR);
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58 stmt.setString(1,LAST_CLEAR);
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59 rs = stmt.executeQuery();
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60 rs.next();
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61 }
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62 lastClear = getLastModified(rs);
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63 stmt.close();
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64 } finally {
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65 con.close();
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66 }
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67 } catch(SQLException e) {
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68 throw new RuntimeException(e);
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69 }
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70 }
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71
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72 private static long getLastModified(ResultSet rs) throws SQLException {
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73 return rs.getTimestamp("last_modified").getTime()/1000*1000;
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74 }
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75
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76 public long[] lastModifieds(final String[] modifyingEvents) {
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77 switch( modifyingEvents.length ) {
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78 case 0:
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79 return new long[0];
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80 case 1:
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81 try {
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82 Connection con = db.getConnection();
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83 PreparedStatement stmt = con.prepareStatement(
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84 "select last_modified from http_cache where event=?"
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85 );
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86 try {
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87 stmt.setString(1,modifyingEvents[0].toString());
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88 ResultSet rs = stmt.executeQuery();
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89 return new long[]{ rs.next() ? getLastModified(rs) : lastClear };
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90 } finally {
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91 stmt.close();
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92 con.close();
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93 }
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94 } catch(SQLException e) {
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95 throw new RuntimeException(e);
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96 }
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97 default:
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98 StringBuilder select = new StringBuilder();
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99 try {
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100 final String[] events = new String[modifyingEvents.length];
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101 final long[] rtn = new long[modifyingEvents.length];
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102 for( int i=0; i<modifyingEvents.length; i++ ) {
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103 events[i] = modifyingEvents[i].toString();
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104 rtn[i] = lastClear;
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105 }
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106 Map<String,Long> map = new HashMap<String,Long>();
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107 select.append(
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108 "select event,last_modified from http_cache where event in ("
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109 ).append( db.arcana().quote(events[0]) );
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110 for( int i=1; i<events.length; i++ ) {
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111 select.append( ',' ).append( db.arcana().quote(events[i]) );
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112 }
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113 select.append( ")" );
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114 Connection con = db.getConnection();
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115 try {
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116 Statement stmt = con.createStatement();
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117 ResultSet rs = stmt.executeQuery( select.toString() );
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118 while( rs.next() ) {
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119 map.put( rs.getString("event"), getLastModified(rs) );
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120 }
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121 stmt.close();
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122 } finally {
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123 con.close();
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124 }
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125 for( int i=0; !map.isEmpty(); i++ ) {
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126 Long lm = map.remove(events[i]);
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127 if( lm != null )
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128 rtn[i] = lm;
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129 }
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130 return rtn;
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131 } catch(SQLException e) {
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132 throw new RuntimeException(select.toString(),e);
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133 }
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134 }
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135 }
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136
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137 public void modified(final String event) {
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138 db.runAfterCommit(new Runnable(){public void run(){
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139 try {
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140 Connection con = db.getConnection();
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141 try {
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142 boolean didUpdate;
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143 {
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144 PreparedStatement stmt = con.prepareStatement(
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145 "update http_cache set last_modified=now() where event = ?"
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146 );
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147 stmt.setString(1,event);
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148 didUpdate = stmt.executeUpdate() > 0;
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149 stmt.close();
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150 }
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151 if( !didUpdate ) {
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152 PreparedStatement stmt = con.prepareStatement(
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153 "insert into http_cache (event) values (?)"
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154 );
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155 stmt.setString(1,event);
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156 DbDatabaseImpl.executeUpdateIgnoringDuplicateKeys(stmt);
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157 stmt.close();
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158 }
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159 } finally {
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160 con.close();
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161 }
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162 } catch(SQLException e) {
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163 throw new RuntimeException("event = "+event,e);
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164 }
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165 }});
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166 }
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167
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168 public void clear() {
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169 try {
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170 Connection con = db.getConnection();
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171 try {
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172 Statement stmt = con.createStatement();
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173 stmt.executeUpdate(
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174 "delete from http_cache"
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175 );
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176 stmt.close();
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177 } finally {
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178 con.close();
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179 }
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180 } catch(SQLException e) {
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181 throw new RuntimeException(e);
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182 }
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183 setLastClear();
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184 }
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185
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186 /*
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187 assumes:
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188
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189 create table http_cache (
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190 event varchar not null primary key,
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191 last_modified timestamp with time zone NOT NULL DEFAULT now()
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192 );
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193 */
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194 }
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