1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
package edu.caltech.nanodb.commands;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;
import edu.caltech.nanodb.indexes.IndexManager;
import edu.caltech.nanodb.relations.ColumnInfo;
import edu.caltech.nanodb.relations.ForeignKeyColumnRefs;
import edu.caltech.nanodb.relations.IndexColumnRefs;
import edu.caltech.nanodb.relations.KeyColumnRefs;
import edu.caltech.nanodb.relations.Schema;
import edu.caltech.nanodb.relations.TableConstraintType;
import edu.caltech.nanodb.relations.TableInfo;
import edu.caltech.nanodb.server.NanoDBServer;
import edu.caltech.nanodb.server.properties.PropertyRegistry;
import edu.caltech.nanodb.storage.TableManager;
import edu.caltech.nanodb.storage.StorageManager;
/**
* This command handles the <tt>CREATE TABLE</tt> DDL operation.
*/
public class CreateTableCommand extends Command {
/** A logging object for reporting anything interesting that happens. */
private static Logger logger = LogManager.getLogger(CreateTableCommand.class);
/** Name of the table to be created. */
private String tableName;
/** If this flag is {@code true} then the table is a temporary table. */
private boolean temporary;
/**
* If this flag is {@code true} then the create-table operation should
* only be performed if the specified table doesn't already exist.
*/
private boolean ifNotExists;
/** List of column-declarations for the new table. */
private List<ColumnInfo> columnInfos = new ArrayList<>();
/** List of constraints for the new table. */
private List<ConstraintDecl> constraints = new ArrayList<>();
/** Any additional properties specified in the command. */
private CommandProperties properties;
/**
* Create a new object representing a <tt>CREATE TABLE</tt> statement.
*
* @param tableName the name of the table to be created
*/
public CreateTableCommand(String tableName) {
super(Command.Type.DDL);
if (tableName == null)
throw new IllegalArgumentException("tableName cannot be null");
this.tableName = tableName;
}
/**
* Returns {@code true} if the table is a temporary table, {@code false}
* otherwise.
*
* @return {@code true} if the table is a temporary table, {@code false}
* otherwise.
*/
public boolean isTemporary() {
return temporary;
}
/**
* Specifies whether the table is a temporary table or not.
*
* @param b {@code true} if the table is a temporary table, {@code false}
* otherwise.
*/
public void setTemporary(boolean b) {
temporary = b;
}
/**
* Returns {@code true} if table creation should only be attempted if it
* doesn't already exist, {@code false} if table creation should always
* be attempted.
*
* @return {@code true} if table creation should only be attempted if it
* doesn't already exist, {@code false} if table creation should
* always be attempted.
*/
public boolean getIfNotExists() {
return ifNotExists;
}
/**
* Sets the flag indicating whether table creation should only be
* attempted if it doesn't already exist.
*
* @param b the flag indicating whether table creation should only be
* attempted if it doesn't already exist.
*/
public void setIfNotExists(boolean b) {
ifNotExists = b;
}
/**
* Sets any additional properties associated with the command. The
* value may be {@code null} to indicate no properties.
*
* @param properties any additional properties to associate with the
* command.
*/
public void setProperties(CommandProperties properties) {
this.properties = properties;
}
/**
* Returns any additional properties specified for the command, or
* {@code null} if no additional properties were specified.
*
* @return any additional properties specified for the command, or
* {@code null} if no additional properties were specified.
*/
public CommandProperties getProperties() {
return properties;
}
/**
* Adds a column description to this create-table command. This method is
* primarily used by the SQL parser.
*
* @param colDecl the details of the column to add
*
* @throws NullPointerException if colDecl is null
*/
public void addColumn(TableColumnDecl colDecl) {
if (colDecl == null)
throw new IllegalArgumentException("colDecl cannot be null");
// Pull out the column-info value first, and add it to the table
// specification. If the table-name doesn't match, update this.
ColumnInfo colInfo = colDecl.getColumnInfo();
if (!tableName.equals(colInfo.getTableName())) {
colInfo = new ColumnInfo(colInfo.getName(), tableName,
colInfo.getType());
}
columnInfos.add(colInfo);
// Next, if any column-level constraints are specified,
// add them to the collection of constraints.
for (ConstraintDecl constraint : colDecl.getConstraints())
addConstraint(constraint);
}
/**
* Returns an immutable list of the column descriptions that are part of
* this <tt>CREATE TABLE</tt> command.
*
* @return an immutable list of the column descriptions that are part of
* this <tt>CREATE TABLE</tt> command.
*/
public List<ColumnInfo> getColumns() {
return Collections.unmodifiableList(columnInfos);
}
/**
* Adds a constraint to this create-table command. This method is primarily
* used by the SQL parser.
*
* @param con the details of the table constraint to add
*
* @throws NullPointerException if con is null
*/
public void addConstraint(ConstraintDecl con) {
if (con == null)
throw new IllegalArgumentException("con cannot be null");
constraints.add(con);
}
/**
* Returns an immutable list of the constraint declarations that are part
* of this <tt>CREATE TABLE</tt> command.
*
* @return an immutable list of the constraint declarations that are part
* of this <tt>CREATE TABLE</tt> command.
*/
public List<ConstraintDecl> getConstraints() {
return Collections.unmodifiableList(constraints);
}
@Override
public void execute(NanoDBServer server) throws ExecutionException {
StorageManager storageManager = server.getStorageManager();
TableManager tableManager = storageManager.getTableManager();
PropertyRegistry propReg = server.getPropertyRegistry();
boolean createIndexesOnKeys = propReg.getBooleanProperty(
NanoDBServer.PROP_CREATE_INDEXES_ON_KEYS);
// See if the table already exists.
if (ifNotExists && tableManager.tableExists(tableName)) {
out.printf("Table %s already exists; skipping create-table.%n",
tableName);
return;
}
// Set up the table's schema based on the command details.
logger.debug("Creating a TableSchema object for the new table " +
tableName + ".");
Schema schema = new Schema();
for (ColumnInfo colInfo : columnInfos) {
try {
schema.addColumnInfo(colInfo);
}
catch (IllegalArgumentException iae) {
throw new ExecutionException("Duplicate or invalid column \"" +
colInfo.getName() + "\".", iae);
}
}
// Do some basic verification of the table constraints:
// * Verify that all named constraints are uniquely named.
// * Open all tables referenced by foreign-key constraints, to ensure
// they exist. (More verification will occur later.)
HashSet<String> constraintNames = new HashSet<>();
HashMap<String, TableInfo> referencedTables = new HashMap<>();
for (ConstraintDecl cd: constraints) {
String name = cd.getName();
if (name != null && !constraintNames.add(name)) {
throw new ExecutionException("Constraint name " + name +
" appears multiple times.");
}
if (cd.getType() == TableConstraintType.FOREIGN_KEY) {
String refTableName = cd.getRefTable();
TableInfo refTblInfo = tableManager.openTable(refTableName);
if (refTblInfo == null) {
throw new ExecutionException("Referenced table " +
refTableName + " doesn't exist.");
}
referencedTables.put(refTableName, refTblInfo);
}
}
// Initialize all the constraints on the table.
initTableConstraints(storageManager, schema, referencedTables);
// Create the table.
logger.debug("Creating the new table " + tableName + " on disk.");
TableInfo tableInfo = tableManager.createTable(tableName, schema, properties);
logger.debug("New table " + tableName + " was created.");
if (createIndexesOnKeys) {
logger.debug("Creating indexes on the new table, and any " +
"referenced tables");
initIndexes(storageManager, tableInfo);
}
out.println("Created table: " + tableName);
}
private void initTableConstraints(StorageManager storageManager,
Schema schema, HashMap<String, TableInfo> referencedTables) {
if (constraints.isEmpty()) {
logger.debug("No table constraints specified, our work is done.");
return;
}
TableManager tableManager = storageManager.getTableManager();
logger.debug("Adding " + constraints.size() +
" constraints to the table.");
HashSet<String> constraintNames = new HashSet<>();
for (ConstraintDecl cd : constraints) {
// Make sure that if constraint names are specified, every
// constraint is actually uniquely named.
if (cd.getName() != null) {
if (!constraintNames.add(cd.getName())) {
throw new ExecutionException("Constraint name " +
cd.getName() + " appears multiple times.");
}
}
TableConstraintType type = cd.getType();
if (type == TableConstraintType.PRIMARY_KEY ||
type == TableConstraintType.UNIQUE) {
// Make a candidate-key constraint and put it on the schema.
int[] cols = schema.getColumnIndexes(cd.getColumnNames());
KeyColumnRefs ck = new KeyColumnRefs(cols, cd.getName(), type);
if (type == TableConstraintType.PRIMARY_KEY) {
// Add NOT NULL constraints for all primary-key columns.
for (int iCol : cols)
schema.addNotNull(iCol);
}
schema.addCandidateKey(ck);
}
else if (type == TableConstraintType.FOREIGN_KEY) {
// Make a foreign key constraint and put it on the schema.
// This involves these steps:
// 1) Create the foreign key on this table's schema.
// 2) Update the referenced table's schema to record that
// this table references that table.
// This should never be null since we already resolved all
// foreign-key table references earlier.
TableInfo refTableInfo = referencedTables.get(cd.getRefTable());
Schema refSchema = refTableInfo.getSchema();
// The makeForeignKey() method ensures that the referenced
// columns are also a candidate key (or primary key) on the
// referenced table.
ForeignKeyColumnRefs fk = DDLUtils.makeForeignKey(schema,
refTableInfo, cd);
schema.addForeignKey(fk);
// Update the referenced table's schema to record that this
// table has a foreign-key reference to the table.
if (refSchema.addReferencingTable(tableName))
tableManager.saveTableInfo(refTableInfo);
}
else if (type == TableConstraintType.NOT_NULL) {
int idx = schema.getColumnIndex(cd.getColumnNames().get(0));
schema.addNotNull(idx);
}
else {
throw new ExecutionException("Unexpected constraint type " +
cd.getType());
}
}
}
private void initIndexes(StorageManager storageManager,
TableInfo tableInfo) {
IndexManager indexManager = storageManager.getIndexManager();
Schema schema = tableInfo.getSchema();
for (ConstraintDecl cd : constraints) {
TableConstraintType type = cd.getType();
if (type == TableConstraintType.PRIMARY_KEY ||
type == TableConstraintType.UNIQUE) {
int[] cols = schema.getColumnIndexes(cd.getColumnNames());
IndexColumnRefs ck = new IndexColumnRefs(cd.getName(), cols);
// Make the index. This also updates the table schema with
// the fact that there is another candidate key on the table.
indexManager.addIndexToTable(tableInfo, ck);
}
else if (type == TableConstraintType.FOREIGN_KEY) {
// Check if there is already an index on the foreign-key
// columns. If there is not, we will create a non-unique
// index on those columns.
int[] fkCols = schema.getColumnIndexes(cd.getColumnNames());
IndexColumnRefs fkColRefs = null; // schema.getIndexOnColumns(new ColumnRefs(fkCols));
if (fkColRefs == null) {
// Need to make a new index for this foreign-key reference
fkColRefs = new IndexColumnRefs(cd.getName(), fkCols);
fkColRefs.setConstraintType(TableConstraintType.FOREIGN_KEY);
// Make the index.
indexManager.addIndexToTable(tableInfo, fkColRefs);
logger.debug(String.format(
"Created index %s on table %s to enforce foreign key.",
fkColRefs.getIndexName(), tableInfo.getTableName()));
}
}
}
}
@Override
public String toString() {
return "CreateTable[" + tableName + "]";
}
/**
* Returns a verbose, multi-line string containing all of the details of
* this table.
*
* @return a detailed description of the table described by this command
*/
public String toVerboseString() {
StringBuilder strBuf = new StringBuilder();
strBuf.append(toString());
strBuf.append('\n');
for (ColumnInfo colInfo : columnInfos) {
strBuf.append('\t');
strBuf.append(colInfo.toString());
strBuf.append('\n');
}
for (ConstraintDecl con : constraints) {
strBuf.append('\t');
strBuf.append(con.toString());
strBuf.append('\n');
}
return strBuf.toString();
}
}